1 00:00:02,247 --> 00:00:04,238 (Ship's horn) 2 00:00:10,727 --> 00:00:12,319 This is Coast. 3 00:00:40,687 --> 00:00:46,205 ln the British lsles, we're familiar with wet weather blown in from the wild seas. 4 00:00:48,887 --> 00:00:53,722 One benefit of a temperate climate is our wonderful labyrinth of rivers. 5 00:00:55,127 --> 00:01:00,155 Giant waterways powered by rain, that all run to the coast. 6 00:01:01,967 --> 00:01:06,404 As rivers and seas collide, great estuaries emerge. 7 00:01:13,007 --> 00:01:18,684 Making our mark on these colossal watery spaces has taken centuries of struggle. 8 00:01:19,967 --> 00:01:25,803 That's left a wealth of extraordinary stories waiting to be discovered along our estuaries. 9 00:01:27,687 --> 00:01:29,757 We're braving three of our greatest.' 10 00:01:30,607 --> 00:01:34,885 the Firth of Forth, the Thames and the Mighty Severn. 11 00:01:36,647 --> 00:01:39,366 And we'll visit grand cities too. 12 00:01:39,887 --> 00:01:46,201 Tessa discovers how the pulling power of estuaries gave the Victorians a capital idea. 13 00:01:46,247 --> 00:01:51,196 Turn the Thames into a giant self-flushing loo. 14 00:01:52,847 --> 00:01:55,486 Where rivers surge into sea lochs, 15 00:01:55,527 --> 00:01:57,404 Miranda swims with the fishes. 16 00:01:59,287 --> 00:02:04,077 The Scottish salmon industry spawned a business worth around half a billion pounds. 17 00:02:04,127 --> 00:02:08,803 But how did they crack the secret of farming a wild sea fish? 18 00:02:10,527 --> 00:02:13,325 And Mark's on the rollercoaster ride under... 19 00:02:13,967 --> 00:02:16,322 Ahh! Wahey! 20 00:02:16,367 --> 00:02:20,724 ..and across the deadly tides of the Severn Estuary. 21 00:02:22,167 --> 00:02:27,844 The story of how it was eventually crossed is one of extraordinary ingenuity 22 00:02:28,527 --> 00:02:30,597 and also explosive tragedy. 23 00:02:32,487 --> 00:02:38,881 We're here to explore what becomes of the coast when rivers and seas collide. 24 00:02:44,167 --> 00:02:50,356 l'm starting my estuary odyssey a pebble's throw from Edinburgh on the Firth of Forth. 25 00:02:52,447 --> 00:02:57,760 The scale of this seaway is staggering, it's impossible to take the whole thing in. 26 00:03:00,447 --> 00:03:04,201 What l could really do with is something tall to climb up 27 00:03:04,247 --> 00:03:06,238 so l can get a bird's eye view. 28 00:03:12,447 --> 00:03:15,883 Only the engineering marvel of the Forth Rail Bridge 29 00:03:15,927 --> 00:03:19,920 doesjustice to the sheer spectacle of the estuary. 30 00:03:21,607 --> 00:03:25,520 As we're coming up here, you can see the rivets on this bridge that hold it together. 31 00:03:25,567 --> 00:03:29,003 6.5 million rivets, and every one of them has been painted by hand. 32 00:03:34,967 --> 00:03:36,480 - ls this it? - This is it, Nick. 33 00:03:36,527 --> 00:03:38,324 Here we are on top of the Forth Bridge. 34 00:03:45,527 --> 00:03:47,518 (Ship's horn) 35 00:03:51,407 --> 00:03:54,558 Up here, right in the middle of the Firth of Forth, 36 00:03:54,607 --> 00:03:59,442 you can get a real sense of the huge scale of this estuary. 37 00:03:59,487 --> 00:04:02,001 l can see the Pentland Hills right over there, 38 00:04:02,047 --> 00:04:05,596 there's the dark volcanic bump of Arthur's Seat 39 00:04:05,647 --> 00:04:08,445 rising above the white buildings of Edinburgh. 40 00:04:09,807 --> 00:04:13,243 Looking west, l can see all the way out to the open sea, the North Sea. 41 00:04:15,127 --> 00:04:19,166 And looking inland in this direction, there's even more. 42 00:04:21,767 --> 00:04:25,442 Here's the Forth Road Bridge arcing over the water in front of me, 43 00:04:25,487 --> 00:04:27,284 behind it Rosyth naval base. 44 00:04:29,167 --> 00:04:33,638 ln the far distance, l can just make out Grangemouth power station, 45 00:04:33,687 --> 00:04:35,678 oozing smoke into the sky. 46 00:04:38,967 --> 00:04:43,597 This estuary is so huge that even from this incredible vantage point, 47 00:04:44,167 --> 00:04:47,239 inland it just fades into invisibility. 48 00:04:47,287 --> 00:04:52,407 The only way of actually getting a true sense of its size is by looking at a map. 49 00:04:56,527 --> 00:05:01,203 This is the mouth of the estuary marked by this little island, the lsle of May, here. 50 00:05:01,247 --> 00:05:05,160 ln the other direction, 60 miles inland, 51 00:05:05,727 --> 00:05:09,117 the water gets less and less salty, gets fresher and fresher 52 00:05:09,847 --> 00:05:13,886 until you reach Stirling here, where this estuary is born. 53 00:05:17,687 --> 00:05:22,317 Starting at its birthplace, l'm flying the length of the waterway. 54 00:05:23,567 --> 00:05:30,040 Will the change in wildlife help pinpoint the elusive spot where river becomes sea? 55 00:05:31,087 --> 00:05:33,999 My guide's marine ecologist Stuart Clough. 56 00:05:35,407 --> 00:05:37,602 And as we pass over Stirling, 57 00:05:37,647 --> 00:05:42,084 the river's very beautiful seen from above, it's like a huge coiled rope. 58 00:05:42,647 --> 00:05:45,445 STUART: You're in classic lower river territory here. 59 00:05:45,487 --> 00:05:49,639 Lower freshwater river, the place where the tide just starts to have its effect. 60 00:05:49,687 --> 00:05:53,475 NlCK: And even now, the mud banks are starting to appear on the side. 61 00:05:53,527 --> 00:05:56,997 STUART: And in those, you've got all kinds of worms and shellfish 62 00:05:57,047 --> 00:05:58,844 that live within those sediments. 63 00:05:58,887 --> 00:06:02,197 They become food for birds. lt's a fantastic environment. 64 00:06:02,887 --> 00:06:07,358 ls it possible to identify the point at which this river, the Forth, 65 00:06:07,407 --> 00:06:10,683 ceases to be a river and begins to be sea? 66 00:06:10,727 --> 00:06:14,606 STUART: From a biologist's perspective, it's a continuum, it changes all the time. 67 00:06:14,647 --> 00:06:16,160 On one hand, it's a no-man's land, 68 00:06:16,207 --> 00:06:20,200 and on the other hand, it's a diverse and rich place with masses of life. 69 00:06:24,447 --> 00:06:27,644 Life is rich where rivers and seas meet. 70 00:06:31,407 --> 00:06:34,843 And where we flock, so does the wildlife. 71 00:06:37,527 --> 00:06:41,759 As we move into saltwater, the big hitters start to surface. 72 00:06:42,647 --> 00:06:48,438 Dolphins, seals and even whales have all been spotted here. 73 00:06:51,367 --> 00:06:54,439 We're now over the sunlit seaside, aren't we, Stuart? 74 00:06:54,487 --> 00:06:56,478 lt's completely changed. 75 00:06:56,527 --> 00:06:59,917 Absolutely, yeah, we're right out in the outer estuary now. 76 00:06:59,967 --> 00:07:02,606 The freshwater influence is a long way behind us, 77 00:07:02,647 --> 00:07:04,080 the beaches are sandy... 78 00:07:04,127 --> 00:07:08,359 NlCK: lf we were down at sea level now, what kind of birds would we be looking at? 79 00:07:08,407 --> 00:07:11,160 Auks, like razorbills, guillemots and puffins, 80 00:07:11,207 --> 00:07:14,563 you've got fulmar, you'll have kittiwakes, you'll have gannets - 81 00:07:14,607 --> 00:07:19,203 real marine species that you'd never find in the freshwater parts of the estuary. 82 00:07:23,407 --> 00:07:29,118 At the edge of the estuary, we get a box office few of the gannets of Bass Rock. 83 00:07:30,687 --> 00:07:36,364 This swirling mass makes the most of food from the sea and shelter from the land. 84 00:07:37,687 --> 00:07:39,439 Where are we now? 85 00:07:39,487 --> 00:07:44,038 STUART: We're just adjacent to the lsle of May, very much the outer limit of the estuary. 86 00:07:45,087 --> 00:07:52,596 We've flown the whole way from the freshwater of a river to the saltwater of the open sea, 87 00:07:53,407 --> 00:07:59,004 over an extraordinary diversity of habitats both human and natural. 88 00:07:59,047 --> 00:08:01,436 Estuaries are worlds of their own. 89 00:08:08,167 --> 00:08:14,720 20 million of us, one third of the UK's population, live on an estuary. 90 00:08:17,327 --> 00:08:20,125 Their flat shorelines are perfect for building, 91 00:08:21,127 --> 00:08:25,917 so each of these coastal highways comes with its own gatekeeper. 92 00:08:30,847 --> 00:08:35,762 Great cities surge up where mighty rivers plunge into the sea. 93 00:08:37,127 --> 00:08:42,565 lt's fitting that the country's capital crowns the most hard-working waterway of all - 94 00:08:43,487 --> 00:08:45,478 the titanic Thames. 95 00:08:48,287 --> 00:08:53,361 For centuries, Londoners have swallowed up the benefits the estuary brings in. 96 00:08:54,567 --> 00:08:56,558 The sea brought riches from abroad, 97 00:08:57,327 --> 00:09:01,286 and the river supplies two-thirds of the city's drinking water. 98 00:09:03,087 --> 00:09:07,444 But the Victorians found a newjob for old Father Thames... 99 00:09:08,447 --> 00:09:10,358 ..doing their dirty work. 100 00:09:14,687 --> 00:09:20,444 Tessa's getting to grips with a grubby tale of triumph and tragedy. 101 00:09:21,847 --> 00:09:27,843 The power of the tide gave an eminent Victorian engineer an extraordinary idea - 102 00:09:28,767 --> 00:09:33,318 turn the Thames into a giant self-flushing loo. 103 00:09:35,327 --> 00:09:39,957 TESSA: The tidal range of the river is huge, around eight metres. 104 00:09:40,487 --> 00:09:46,005 This powerful ebb and flow gave rise to an ingenious sewer plan. 105 00:09:46,727 --> 00:09:49,321 Release excrement as the tide turns, 106 00:09:49,847 --> 00:09:54,841 and let the outgoing flow flush London's waste way out to sea. 107 00:09:57,047 --> 00:10:02,121 The city's relationship with the sea spawned a sewer system that was the envy of the world. 108 00:10:02,167 --> 00:10:05,000 Opened in 1 865 by the Prince of Wales, 109 00:10:05,047 --> 00:10:10,167 this subterranean labyrinth elevated its mastermind, Joseph Bazalgette, 110 00:10:11,207 --> 00:10:14,199 to become a hero of the Victorian age. 111 00:10:17,807 --> 00:10:21,846 Bazalgette's master plan demanded a warren of waste pipes, 112 00:10:22,327 --> 00:10:28,880 a network over 1,000 miles long to carry the capital's raw sewage out to the Thames. 113 00:10:29,607 --> 00:10:31,643 lt took six years to build, 114 00:10:31,687 --> 00:10:37,284 constructed so well, it still forms the backbone of London's sewer complex. 115 00:10:38,487 --> 00:10:44,483 Over 300 million bricks, placed so precisely they form water-tight tunnels. 116 00:10:47,727 --> 00:10:49,922 You know how to treat a girl, don't you, Rob? 117 00:10:49,967 --> 00:10:52,083 l do, l take them only to the best spots. 118 00:10:53,647 --> 00:10:57,845 lmpressive as this labyrinth is, it's only the means to a watery end. 119 00:10:58,687 --> 00:11:01,599 The city's sewage still needed sweeping out to sea, 120 00:11:01,647 --> 00:11:05,925 so it was piped towards the coast to pass the problem onto the tide. 121 00:11:06,927 --> 00:11:12,524 The muck flowed downstream to arrive at the final triumph of the entire system, 122 00:11:13,127 --> 00:11:15,516 the pumping station at Crossness. 123 00:11:24,367 --> 00:11:27,165 This is staggering! 124 00:11:27,927 --> 00:11:29,918 lt's like some sort of ballroom. 125 00:11:36,647 --> 00:11:40,925 lt's a real indication of the level of pride they took in their work. 126 00:11:40,967 --> 00:11:42,878 The beauty is just breathtaking. 127 00:11:43,607 --> 00:11:48,886 And these huge pumps are even named after members of the royal family. 128 00:11:52,767 --> 00:11:57,079 The pumping stations were the final stage of Balzalgette's grand plan. 129 00:11:57,607 --> 00:12:00,201 They pushed the sewage up into huge reservoirs, 130 00:12:00,927 --> 00:12:04,237 to be stored until the tide began to turn. 131 00:12:07,167 --> 00:12:08,646 (Ship's horn) 132 00:12:09,247 --> 00:12:13,843 When the tide started to ebb, they released the sewage into the Thames just there. 133 00:12:14,487 --> 00:12:20,517 They relied on the surge of seawater to whisk Londoners' muck out of sight and out of mind. 134 00:12:21,207 --> 00:12:24,756 This was Joseph Bazalgette's big tidal flush. 135 00:12:25,247 --> 00:12:30,196 His plan to turn the Thames into one gigantic toilet bowl was complete. 136 00:12:32,047 --> 00:12:35,084 Bazalgette was heralded as the city's saviour. 137 00:12:35,887 --> 00:12:39,436 But is there a skeleton lurking in London's water closet? 138 00:12:41,287 --> 00:12:44,324 Life may have been rosy for those in central London, 139 00:12:44,367 --> 00:12:48,406 but it didn't smell so sweet for those living downstream. 140 00:12:52,487 --> 00:12:56,480 Like a real-life toilet, the Thames is full of U-bends. 141 00:12:57,407 --> 00:13:01,241 The waste wasn't clearing as fast as Bazalgette had imagined, 142 00:13:01,767 --> 00:13:05,123 and the consequences turned out to be devastating. 143 00:13:07,527 --> 00:13:10,087 lt's 3rd September 1 878. 144 00:13:11,727 --> 00:13:15,606 The pleasure steamer the Princess Alice is on its way back to London, 145 00:13:15,647 --> 00:13:17,239 crammed with passengers. 146 00:13:17,927 --> 00:13:22,045 The day-trippers had been enjoying fresh air at the mouth of the estuary, 147 00:13:22,087 --> 00:13:27,844 but returning to the city, near the sewage outlet, the pleasure steamer was struck by disaster. 148 00:13:27,887 --> 00:13:29,878 (Creaking and splintering of wood) 149 00:13:31,207 --> 00:13:33,198 lt collides with another boat. 150 00:13:33,247 --> 00:13:37,684 Hundreds are flung into the river, many will be drowned. 151 00:13:37,727 --> 00:13:39,718 But it's even worse than that. 152 00:13:43,167 --> 00:13:46,682 Revealing the gruesome fate of those floundering in the estuary 153 00:13:46,727 --> 00:13:49,241 is local historian Joz Joslin. 154 00:13:50,607 --> 00:13:54,486 So the vessel's upended, and hundreds of people are in the water? 155 00:13:54,527 --> 00:13:57,405 Yes, and lots of them are women and children. 156 00:13:57,447 --> 00:13:59,199 And they're screaming. 157 00:13:59,247 --> 00:14:03,525 Unfortunately it's not water that they're in, they're in actually sewage. 158 00:14:03,567 --> 00:14:05,558 So there was no oxygen. 159 00:14:06,287 --> 00:14:09,006 Lots of them died because there was no air to breathe. 160 00:14:09,047 --> 00:14:10,321 Ohh! 161 00:14:10,367 --> 00:14:12,756 So they're either being suffocated or drowning? 162 00:14:12,807 --> 00:14:15,321 - Or poisoned. - How revolting! 163 00:14:15,367 --> 00:14:18,086 - And the majority died? - Yes, the majority died. 164 00:14:18,127 --> 00:14:22,245 So they said that every street in the East End of London had lost somebody, 165 00:14:22,287 --> 00:14:26,121 because it was their Sunday school outings that were on board the vessel. 166 00:14:27,327 --> 00:14:29,921 The pleasure boat sank close to the sewage works, 167 00:14:29,967 --> 00:14:32,401 and the timing could not have been worse. 168 00:14:35,167 --> 00:14:39,126 The Beckton sewage outlet pipe carrying all North London's waste 169 00:14:39,167 --> 00:14:42,239 had just discharged its stinking load into the river. 170 00:14:45,287 --> 00:14:50,645 Over 600 people choked to death in a toxic soup of human filth. 171 00:14:56,607 --> 00:15:00,805 After the tragedy, Bazalgette's sewage system came under the spotlight. 172 00:15:03,327 --> 00:15:08,276 Members of the local historical society read the words of their forefathers. 173 00:15:09,607 --> 00:15:13,043 ''There had been an accumulation of black greasy filth along the shore. 174 00:15:13,087 --> 00:15:17,046 The filth settles on the steps as the tide goes down.'' 175 00:15:17,087 --> 00:15:19,362 ''The river in hot weather is very bad. 176 00:15:19,407 --> 00:15:22,399 ln some places, it smells so bad you cannot stand it.'' 177 00:15:23,527 --> 00:15:27,520 A commission of inquiry delivered a damning indictment, concluding.' 178 00:15:27,567 --> 00:15:30,718 ''lt is neither necessary orjustifiable 179 00:15:30,767 --> 00:15:36,000 to discharge sewage in its crude state into any parts of the Thames. '' 180 00:15:37,527 --> 00:15:41,281 The Pall Mall Gazette took Bazalgette to task, stating.' 181 00:15:41,887 --> 00:15:47,120 ''The natural man in him puts off the evil day of having to admit failure. '' 182 00:15:48,207 --> 00:15:51,517 Luckily for Bazalgette, the muck didn't stick, 183 00:15:52,247 --> 00:15:56,240 but London did pull the plug on his big tidal flush. 184 00:15:57,287 --> 00:16:00,085 ln 1 887, a new system started. 185 00:16:00,687 --> 00:16:04,566 Now the solid human waste was pumped into vessels like this. 186 00:16:05,327 --> 00:16:09,081 The excrement was shipped out to the open sea and dumped. 187 00:16:09,807 --> 00:16:12,321 They were known locally as ''Bovril Boats''... 188 00:16:12,367 --> 00:16:14,358 amongst other things. 189 00:16:14,407 --> 00:16:18,082 We used to call them... Well, never mind what we used to call them! 190 00:16:18,127 --> 00:16:20,243 - What did you call them? - No, l'm not saying. 191 00:16:20,927 --> 00:16:23,839 They used to come and moor, they had moorings for them, 192 00:16:23,887 --> 00:16:25,957 and they would take the residue of it. 193 00:16:26,007 --> 00:16:30,717 Cos all the fluids were taken off, so it was almost solid the stuff that they took out, 194 00:16:30,767 --> 00:16:32,485 human detritus, 195 00:16:32,527 --> 00:16:34,279 so that it wasn't into the river. 196 00:16:35,967 --> 00:16:39,926 Sewage-carrying ships didn't just do the dirty work of London. 197 00:16:40,567 --> 00:16:43,240 They were once a common sight on our estuaries, 198 00:16:43,287 --> 00:16:47,405 cleaning up Glasgow, Belfast and other coastal cities. 199 00:16:51,487 --> 00:16:55,844 London's Bovril Boats were finally pensioned off in 1 998. 200 00:16:59,087 --> 00:17:04,480 Balzalgette's tunnels still bring raw sewage here to the Crossness Works, 201 00:17:04,527 --> 00:17:08,440 but now the solid matter's burnt off to make electricity. 202 00:17:10,407 --> 00:17:13,319 The liquid sewage is treated, it goes from this... 203 00:17:14,327 --> 00:17:15,601 ..to this. 204 00:17:16,927 --> 00:17:22,797 The cleaned-up fluid still gets the big tidal heave-ho and is discharged into the Thames, 205 00:17:22,847 --> 00:17:24,838 where the river and the sea collide. 206 00:17:37,687 --> 00:17:41,965 NlCK: Tide and traffic on the Thames flow two ways. 207 00:17:44,447 --> 00:17:46,438 ln deep waters at the estuary mouth, 208 00:17:47,167 --> 00:17:53,003 ships from around the world come to unburden themselves on the docks at Sheerness. 209 00:17:55,367 --> 00:17:57,164 But back in the 1 9th century, 210 00:17:57,207 --> 00:18:01,917 a group of foreign stowaways snuck off a ship and never left. 211 00:18:02,687 --> 00:18:06,202 They set up a secret community within the harbour walls. 212 00:18:07,487 --> 00:18:11,480 This is the des-res of Britain's only colony... of scorpions. 213 00:18:14,887 --> 00:18:16,878 But not the monster kind. 214 00:18:19,047 --> 00:18:25,566 European Yellowtail scorpions arrived here from ltaly on a masonry ship some 200 years ago. 215 00:18:28,687 --> 00:18:33,522 Now the offspring of those ltalian scorpions have found a British admirer. 216 00:18:34,607 --> 00:18:36,325 That's amore 217 00:18:36,367 --> 00:18:38,358 Hi, l'm Bex, and l'm a scorpo-holic. 218 00:18:39,127 --> 00:18:44,326 l've been fascinated by scorpions since l was a teenager and been hooked ever since. 219 00:18:45,367 --> 00:18:48,677 l'm here to see Britain's only colony of scorpions, 220 00:18:48,727 --> 00:18:50,718 but l've got to wait for the sun to go down. 221 00:18:50,767 --> 00:18:52,997 Ting-a-ling-a-ling, and you'll sing... 222 00:18:53,767 --> 00:18:57,316 lt's properly dark now, so l'm going to see if l can find some. 223 00:18:57,367 --> 00:19:01,758 l'm using a UV torch cos scorpions glow under ultraviolet light. 224 00:19:02,527 --> 00:19:04,085 l think l've just spotted one. 225 00:19:04,687 --> 00:19:08,202 Definitely an adult, probably out looking for something to eat. 226 00:19:09,167 --> 00:19:12,762 lt is pretty cool, though, isn't it, having scorpions in the UK? 227 00:19:14,047 --> 00:19:17,881 They are a member of the spider family, they have got eight legs, not six. 228 00:19:18,607 --> 00:19:20,086 They eat woodlice. 229 00:19:20,127 --> 00:19:23,324 They're ambush predators, so they will just sit and wait 230 00:19:23,367 --> 00:19:26,996 and then something will come past and they'll just jump out and grab it 231 00:19:27,047 --> 00:19:29,766 and subdue it with their claws rather than stinging it. 232 00:19:29,807 --> 00:19:32,719 They don't generally use their stings, these ones. 233 00:19:32,767 --> 00:19:34,758 That's amore 234 00:19:35,287 --> 00:19:37,084 That's amore 235 00:19:37,127 --> 00:19:39,357 Very happy that we found some. 236 00:19:39,407 --> 00:19:44,401 This is a tiny little incy one, it's so cute, and with tininess comes speed. 237 00:19:49,887 --> 00:19:52,799 lt's been a great night, we've seen loads of scorpions. 238 00:19:52,847 --> 00:19:56,840 But l think l'll put this one back before it legs it. 239 00:19:58,847 --> 00:20:00,485 Bye, little fella. 240 00:20:00,527 --> 00:20:02,324 That's amore 241 00:20:02,367 --> 00:20:04,358 l think l'll leg it now, too. 242 00:20:04,407 --> 00:20:06,398 That's amore 243 00:20:20,007 --> 00:20:26,276 We're on a journey to discover what becomes of the coast when rivers and seas collide. 244 00:20:29,287 --> 00:20:33,599 l'm exploring the Firth of Forth on Scotland's east coast, 245 00:20:34,447 --> 00:20:40,682 where canny folk profited from their prime location, ideal for seaborne business. 246 00:20:41,567 --> 00:20:46,721 And with rich seams of coal for power, the population boomed. 247 00:20:47,527 --> 00:20:51,122 With more mouths to feed, getting enough fresh food was tricky, 248 00:20:52,247 --> 00:20:55,364 so they looked to the sea to preserve their provisions. 249 00:20:58,047 --> 00:21:00,959 You'll find the evidence at St Monans. 250 00:21:05,607 --> 00:21:10,078 Here food processing created a curious landscape. 251 00:21:13,127 --> 00:21:19,566 The shore is lined with lots and lots of very strange grass-covered humps, 252 00:21:19,607 --> 00:21:22,485 with what seems to be a ruined building over there. 253 00:21:23,167 --> 00:21:25,727 And up there, a stone windmill. 254 00:21:28,247 --> 00:21:32,035 The ruins of industrial activity reveal themselves the more you look. 255 00:21:36,447 --> 00:21:41,726 This land was remodelled by people making the most of one bounty from the sea 256 00:21:41,767 --> 00:21:44,884 that isn't in short supply - salt. 257 00:21:46,367 --> 00:21:49,598 Before refrigeration, salt was a valuable commodity, 258 00:21:50,927 --> 00:21:54,158 preserving herring landed along the East Coast. 259 00:21:55,807 --> 00:21:58,480 Scottish salt was also exported to England, 260 00:21:59,407 --> 00:22:01,921 turning a tasty profit for the salt works. 261 00:22:04,847 --> 00:22:07,759 Those strange hummocks come in sets, 262 00:22:07,807 --> 00:22:11,800 each set of hummocks is the ruins of a pan house. 263 00:22:11,847 --> 00:22:14,122 lnside each of those pan houses, 264 00:22:14,167 --> 00:22:19,400 there was an iron pan about six metres by three metres, with coal fires beneath it. 265 00:22:19,447 --> 00:22:22,757 Sea water was pumped, probably using this windmill, 266 00:22:22,807 --> 00:22:25,719 from the sea in pipes up to each pan house. 267 00:22:25,767 --> 00:22:29,646 Once it had been boiled off in the pans, you had salt. 268 00:22:33,287 --> 00:22:36,085 A rare film brings the enterprise back to life. 269 00:22:38,967 --> 00:22:42,801 Salt works once flourished along Scotland's east coast. 270 00:22:44,087 --> 00:22:49,764 The last operation, at Prestonpans, didn't close its doors until 1 97 4. 271 00:22:52,767 --> 00:22:56,726 lt was the abundance of coal along this estuary 272 00:22:57,287 --> 00:23:00,882 that made it a good site for boiling up seawater. 273 00:23:02,687 --> 00:23:05,679 A sample of seawater stirs up a mystery, 274 00:23:05,727 --> 00:23:08,321 right at the heart of this forgotten industry. 275 00:23:11,007 --> 00:23:13,202 Out there is the sea full of salt. 276 00:23:15,487 --> 00:23:17,478 And l can certainly taste it. 277 00:23:18,087 --> 00:23:20,157 This little brook running into the sea... 278 00:23:22,647 --> 00:23:24,638 ..doesn't taste salty at all. 279 00:23:25,527 --> 00:23:27,836 So why is freshwater fresh... 280 00:23:29,087 --> 00:23:32,284 ..and why is seawater salty? 281 00:23:35,967 --> 00:23:42,156 lt's one of those brilliantly simple, infuriating questions that kids ask.' 282 00:23:42,687 --> 00:23:44,359 why is the sea salty? 283 00:23:45,287 --> 00:23:47,323 l'm enlisting the help of a grown-up. 284 00:23:48,247 --> 00:23:51,444 Simon Boxall's from the National Oceanography Centre. 285 00:23:52,327 --> 00:23:53,965 He should be able to work it out. 286 00:23:54,007 --> 00:23:57,920 We've all swum in the sea, we know it doesn't taste like freshwater, Simon. 287 00:23:57,967 --> 00:23:59,605 But why is it salty? 288 00:23:59,647 --> 00:24:02,366 You have to go right back to the beginning stage of the earth, 289 00:24:02,407 --> 00:24:04,398 back several billion years. 290 00:24:04,447 --> 00:24:08,076 lf you go back that far, the earth was a completely different place. 291 00:24:08,127 --> 00:24:10,004 lt was full of volcanic eruptions, 292 00:24:10,047 --> 00:24:11,765 there was lots of steam around, 293 00:24:11,807 --> 00:24:14,321 but also there was a lot of sodium in the rocks. 294 00:24:14,367 --> 00:24:17,439 And that sodium was being hit by the hydrochloric acid 295 00:24:17,487 --> 00:24:19,682 that was given off by these volcanic vents. 296 00:24:20,527 --> 00:24:22,802 lf we take these two very harmful chemicals - 297 00:24:22,847 --> 00:24:25,725 on the one hand, you've got the element of sodium, very reactive, 298 00:24:25,767 --> 00:24:29,077 on the other hand, there's chlorine, very dangerous and very reactive. 299 00:24:29,127 --> 00:24:32,802 Put the two together and you create something, sodium chloride, 300 00:24:32,847 --> 00:24:36,840 which is the sort of thing you sprinkle on your chips and certainly isn't harmful at all. 301 00:24:36,887 --> 00:24:40,880 So you've got this hydrochloric acid pouring out of the volcanic vents 302 00:24:40,927 --> 00:24:45,284 meeting the sodium hydroxide which is already lying in the rocks on the sea bed, 303 00:24:45,327 --> 00:24:48,399 creating this stuff called sodium chloride, which is salt. 304 00:24:49,487 --> 00:24:54,880 These ancient chemical reactions gave birth to our salty seas. 305 00:24:56,407 --> 00:24:59,717 We can create those sort of primordial days. 306 00:24:59,767 --> 00:25:02,076 We can actually take some hydrochloric acid, 307 00:25:02,127 --> 00:25:05,005 the sort of stuff that came out of the vents of the volcanoes. 308 00:25:05,047 --> 00:25:09,359 We've got some dilute sodium hydroxide, which represents the stuff that was in the rocks. 309 00:25:09,407 --> 00:25:11,284 Between us, we can make some salt. 310 00:25:11,327 --> 00:25:13,522 We can take these two quite nasty chemicals 311 00:25:13,567 --> 00:25:17,037 and we can produce something really vital to life, in many ways. 312 00:25:17,087 --> 00:25:19,362 This is hydrochloric acid, very dilute. 313 00:25:19,407 --> 00:25:22,444 And we're going to pop it into this vessel here. 314 00:25:23,447 --> 00:25:24,641 OK. 315 00:25:24,687 --> 00:25:27,520 We're going to then add our sodium hydroxide. 316 00:25:27,567 --> 00:25:31,765 Now, at the moment, basically, the sodium and the chlorine are combining. 317 00:25:31,807 --> 00:25:33,957 That's giving off heat, can you feel that? 318 00:25:34,007 --> 00:25:36,316 lt's warm, really warm. Wow! 319 00:25:36,367 --> 00:25:39,677 We've effectively neutralised that acid, that sodium hydroxide, 320 00:25:39,727 --> 00:25:44,084 and what we have in there now is basically water and salt. 321 00:25:46,087 --> 00:25:52,196 We've compressed billions of years of the earth's evolution to make a miniature ocean. 322 00:25:53,447 --> 00:25:58,362 Boiling off our DlYseawater leaves the prize ingredient. 323 00:26:01,007 --> 00:26:04,602 So here it is - our very own home-made salt. 324 00:26:06,007 --> 00:26:11,877 White crystals that washed wealth in from the sea to help feed an estuary. 325 00:26:24,167 --> 00:26:28,763 The salty shoreline satisfies our appetite in surprising ways. 326 00:26:30,087 --> 00:26:36,765 On sea marshes in Wales, sheep graze on grass made sturdy by regular salt baths. 327 00:26:38,287 --> 00:26:42,724 This distinctly coastal vegetation gives the lamb a unique flavour. 328 00:26:45,967 --> 00:26:52,645 But to explore the biggest effect our shoreline has on our waistline, head north to Scotland. 329 00:26:55,927 --> 00:27:00,125 A natural wonder plays out where rivers meet the sea, 330 00:27:00,767 --> 00:27:03,076 like here at Lochcarron. 331 00:27:05,047 --> 00:27:09,518 Miranda is immersed in the secret life of the salmon. 332 00:27:12,607 --> 00:27:15,405 l'm in the thick of Britain's favourite fish dish. 333 00:27:16,047 --> 00:27:18,038 Our insatiable appetite for salmon 334 00:27:18,087 --> 00:27:23,002 has spawned an industry in the UK worth around half a billion pounds a year. 335 00:27:23,567 --> 00:27:26,639 But farming these fish is a lot more difficult than you think. 336 00:27:28,327 --> 00:27:33,606 MlRANDA: Salmon are challenging to rear in farms because of their extraordinary life cycle. 337 00:27:34,127 --> 00:27:36,118 They're born in freshwater rivers, 338 00:27:36,167 --> 00:27:38,158 then migrate to the sea. 339 00:27:39,367 --> 00:27:43,997 To survive in saltwater, a salmon's body goes through radical changes. 340 00:27:47,687 --> 00:27:51,646 That transformation is very tricky to manage in captivity. 341 00:27:52,167 --> 00:27:55,079 To see why, l'm seeking out the wild fish. 342 00:27:57,207 --> 00:27:59,323 Take a winter walk along a salmon river 343 00:27:59,367 --> 00:28:03,246 and there might be delicate little eggs lurking deep in the watery gravel. 344 00:28:04,207 --> 00:28:08,485 So why do salmon out at sea bother to come all this way to lay their eggs? 345 00:28:09,327 --> 00:28:12,444 l'm meeting wild salmon expert Bob Kindness. 346 00:28:13,407 --> 00:28:17,161 What a place for the salmon to come back and lay their eggs in the gravel here. 347 00:28:17,207 --> 00:28:19,198 BOB: They have to be spawned in fresh water. 348 00:28:19,247 --> 00:28:23,445 The eggs would not survive other than being in fresh water, they wouldn't survive in the sea. 349 00:28:23,487 --> 00:28:28,038 So the salmon has to make that journey, it has to come back from the feeding grounds, 350 00:28:28,087 --> 00:28:32,239 usually back to its home river, back to the area where it itself was born. 351 00:28:35,647 --> 00:28:39,435 Once hatched, these freshwater fish face a big problem. 352 00:28:40,207 --> 00:28:43,085 They need to get out to sea where there's more food, 353 00:28:43,847 --> 00:28:46,839 but their bodies are incapable of dealing with salt water. 354 00:28:48,487 --> 00:28:51,957 Ajelly sweet experiment gives us a taste of their challenge. 355 00:28:53,407 --> 00:28:56,843 This tiny jelly bear has a dense sugary body. 356 00:28:57,327 --> 00:29:02,401 Soak him in water overnight and he looks like this, all swollen up. 357 00:29:03,287 --> 00:29:07,326 This plump bear is our happily hydrated freshwater salmon. 358 00:29:09,287 --> 00:29:12,006 But if l add salt to create seawater, 359 00:29:12,047 --> 00:29:16,325 the fresh water is sucked out of the sweet, and it shrivels. 360 00:29:17,607 --> 00:29:21,725 Death by dehydration is the challenge a salmon faces 361 00:29:21,767 --> 00:29:23,883 going from the river down into the sea. 362 00:29:26,087 --> 00:29:29,557 To avoid dehydration, salmon develop two defences. 363 00:29:30,327 --> 00:29:34,206 Their scales toughen to stop freshwater leaching out of their body. 364 00:29:34,247 --> 00:29:39,605 Also their kidneys and gills adapt so they can cope with life in saltwater. 365 00:29:41,967 --> 00:29:46,563 To see the scale of the transformation, we've anaesthetized two of the fish. 366 00:29:47,727 --> 00:29:51,720 Gosh, you can really see the difference, can't you now, side-by-side? 367 00:29:51,767 --> 00:29:54,679 The speckled brown tiddler is a freshwater salmon, 368 00:29:55,567 --> 00:29:59,799 the silver beauty below, just a year older, is ready for the sea. 369 00:30:04,647 --> 00:30:07,605 A salmon can turn around and go back 370 00:30:07,647 --> 00:30:10,878 if its body isn't adapting to life in the seawater, 371 00:30:10,927 --> 00:30:13,395 and some fish take years to make it out to sea. 372 00:30:16,287 --> 00:30:17,925 That's OKin the wild, 373 00:30:17,967 --> 00:30:23,246 but how could fish farmers know when it was safe to move their salmon to saltwater pens? 374 00:30:25,567 --> 00:30:30,004 ln the early 1 970s, years of experiments finally paid off. 375 00:30:32,527 --> 00:30:36,202 l've got a patent here applied for in 1 97 1 . 376 00:30:36,247 --> 00:30:42,243 This is a scientific recipe for the crucial step in the growing of captive salmon. 377 00:30:43,607 --> 00:30:46,724 The Fish Equation says when the weight of the salmon, W, 378 00:30:47,407 --> 00:30:51,559 x 1 00, divided by its length, L, cubed, 379 00:30:52,087 --> 00:30:55,363 is equal to 0.8, it's ready for sea water. 380 00:30:57,767 --> 00:31:00,042 Armed with the power to control nature, 381 00:31:00,087 --> 00:31:03,363 salmon farming in Scotland rapidly became big business. 382 00:31:04,847 --> 00:31:09,398 As the scale of production rose, the price of the fish started to plummet. 383 00:31:11,687 --> 00:31:16,044 NEWSREEL: The market shows every sign of expanding as the supply increases. 384 00:31:16,087 --> 00:31:19,966 And now, salmon is not just to be found in the exclusive fishmongers, 385 00:31:20,687 --> 00:31:23,440 but can be bought vacuum-packed in the supermarkets. 386 00:31:24,207 --> 00:31:28,086 MlRANDA: Salmon stopped being a treat saved for special occasions. 387 00:31:28,127 --> 00:31:30,118 Now it was as cheap as chicken. 388 00:31:33,287 --> 00:31:38,884 So how did fish farmers manage to mimic nature with their production line process? 389 00:31:40,087 --> 00:31:42,476 The salmon start life in freshwater tanks. 390 00:31:43,687 --> 00:31:46,360 When they're big enough to satisfy the Fish Equation, 391 00:31:46,407 --> 00:31:48,557 they're sucked up and piped into trucks. 392 00:31:51,807 --> 00:31:53,399 Trucks take them to boats, 393 00:31:54,127 --> 00:31:59,076 boats ferry them to saltwater enclosures anchored at the sea end of the estuary. 394 00:32:02,687 --> 00:32:06,157 The salmon are kept in these pens for up to 22 months, 395 00:32:06,207 --> 00:32:08,482 but they're quite used to human company. 396 00:32:09,247 --> 00:32:13,718 There are divers who regularly check on the fish and the nets that hold them in. 397 00:32:15,167 --> 00:32:17,158 The salmon are constantly watched. 398 00:32:17,847 --> 00:32:23,797 CC TV operators check they're eating - and make sure they're not being eaten - by seals. 399 00:32:24,847 --> 00:32:27,964 Farmed fish carry more lice than wild ones, 400 00:32:28,007 --> 00:32:30,202 so they're monitored for sickness too. 401 00:32:33,727 --> 00:32:37,515 Our appetite for salmon makes all this effort profitable. 402 00:32:38,367 --> 00:32:41,916 lf our demand for these fish is such that we need to farm them, 403 00:32:41,967 --> 00:32:48,156 then salmon pens will become an even more common site where rivers and seas collide. 404 00:33:03,967 --> 00:33:07,755 NlCK: We're on a journey around three of our mightiest estuaries... 405 00:33:10,887 --> 00:33:15,085 ..where tideways bring bounty from the sea deep inland. 406 00:33:18,807 --> 00:33:24,677 So imagine the potential of connecting two great estuaries to form one super-highway. 407 00:33:26,367 --> 00:33:32,715 That unifying vision excited the imagination of merchants in the Firth of Forth. 408 00:33:34,927 --> 00:33:39,398 ln 1 768, businessmen began to build their own waterway, 409 00:33:40,167 --> 00:33:46,037 an epic canal joining the Forth to another great estuary, the Clyde. 410 00:33:49,367 --> 00:33:54,361 What those early entrepreneurs couldn't know was that their scheme to connect two estuaries 411 00:33:54,407 --> 00:33:59,720 would one day lead to a revolution in fibre-optic communication. 412 00:34:04,127 --> 00:34:10,396 The story starts with an extraordinary discovery on the waterway, some 1 80 years ago. 413 00:34:11,487 --> 00:34:15,639 Let's go back to that fateful day in 1 834. 414 00:34:15,687 --> 00:34:19,236 Young engineer John Scott Russell - this is him later in life - 415 00:34:19,287 --> 00:34:21,721 was on the towpath of this canal. 416 00:34:23,807 --> 00:34:26,162 Russell was watching a barge, 417 00:34:26,207 --> 00:34:31,839 when suddenly its bow wave detached from the front of the boat and sped off on its own. 418 00:34:34,007 --> 00:34:37,283 lt was a solitary hump of travelling water. 419 00:34:38,367 --> 00:34:40,562 The engineer would become obsessed 420 00:34:40,607 --> 00:34:44,236 trying to understand the solitary wave through mathematics. 421 00:34:45,367 --> 00:34:47,597 But on first sighting, he had to act fast. 422 00:34:49,007 --> 00:34:52,556 Russell jumped on his horse and gave chase to the wave. 423 00:34:54,407 --> 00:34:57,285 Normally waves peter out or break up, 424 00:34:57,807 --> 00:35:01,880 but this mysterious wave retained its shape and sped onwards. 425 00:35:02,687 --> 00:35:04,643 After a chase of about two miles, 426 00:35:05,287 --> 00:35:09,200 the solitary wave still showed no signs of petering out. 427 00:35:09,247 --> 00:35:12,956 Eventually, it escaped Russell's pursuit altogether. 428 00:35:13,007 --> 00:35:19,560 Russell would have recognised that this peculiar wave was similar to the Severn bore. 429 00:35:24,287 --> 00:35:28,997 That solitary wave is produced when the tide collides with the River Severn, 430 00:35:29,647 --> 00:35:34,516 sending a surge of seawater up the narrow funnel of the Bristol Channel. 431 00:35:35,687 --> 00:35:38,838 Not unlike the narrow channel of the canal. 432 00:35:39,927 --> 00:35:44,398 So Russell experimented with canal-shaped water tanks. 433 00:35:45,007 --> 00:35:49,922 Mathematician Chris Eilbeck thinks he can recreate Russell's solitary wave. 434 00:35:50,887 --> 00:35:53,560 - Keep our fingers crossed. - Off you go, l'm dying to see one. 435 00:35:57,447 --> 00:36:01,122 - So you can see the wave there... - Look at that, you got it first time. 436 00:36:01,167 --> 00:36:03,158 Just a hump of water on its own. 437 00:36:03,207 --> 00:36:05,357 You can feel the force of it when it hits. 438 00:36:05,407 --> 00:36:07,921 - Now it's gone all the way back. - lt's amazingly stable. 439 00:36:07,967 --> 00:36:09,639 lt'll keep going for miles. 440 00:36:10,607 --> 00:36:14,885 The canal's dimensions were perfect for keeping the wave stable, 441 00:36:16,207 --> 00:36:19,677 deep enough for the wave not to steepen too sharply and break, 442 00:36:19,727 --> 00:36:22,878 but shallow enough that it didn't flatten out. 443 00:36:23,727 --> 00:36:28,118 Amazingly, these waves remain self-contained and intact, 444 00:36:28,527 --> 00:36:30,518 even when they collide. 445 00:36:30,567 --> 00:36:32,398 Three, two, one, go! 446 00:36:34,607 --> 00:36:38,646 CHRlS: And you can see that after the collision, they just reappear on the other side. 447 00:36:38,687 --> 00:36:42,043 Chris, are you saying that the waves didn't just bounce off each other 448 00:36:42,087 --> 00:36:43,725 but went through each other? 449 00:36:43,767 --> 00:36:47,760 Yes that's correct, they go through each other and reappear on the other side. 450 00:36:47,807 --> 00:36:51,038 - Undiminished? - Yes, and mathematically exact. 451 00:36:51,087 --> 00:36:52,486 Unbelievable. 452 00:36:56,567 --> 00:37:02,039 These remarkable packets of travelling energy have been christened solitons. 453 00:37:03,327 --> 00:37:06,160 Now is the time to scale our experiment up. 454 00:37:07,207 --> 00:37:11,166 Let's try and recreate the full wonder of the soliton wave 455 00:37:11,207 --> 00:37:15,246 on this 800-foot-long straight section of Scottish canal. 456 00:37:18,367 --> 00:37:20,358 But it won't be easy. 457 00:37:21,527 --> 00:37:25,520 The wave John Scott Russell chased back in 1 834 458 00:37:25,567 --> 00:37:30,004 was created when a horse-drawn boat came to a sudden stop, 459 00:37:30,567 --> 00:37:32,558 releasing its bow wave. 460 00:37:33,527 --> 00:37:37,918 We're trying a more modern approach - a motor boat loaded with people 461 00:37:37,967 --> 00:37:40,800 to provide ballast, and to bear witness. 462 00:37:41,927 --> 00:37:45,920 Now, Rachel, you're sitting in the front of the boat here with some top hats. 463 00:37:45,967 --> 00:37:49,676 You're clearly expecting something to happen. What have you got the hats for? 464 00:37:49,727 --> 00:37:54,437 We've got the hats as a tribute to John Scott Russell, who discovered the first soliton wave. 465 00:37:54,487 --> 00:37:58,765 We'll be throwing them up in the air with joy when we recreate it, is the plan. 466 00:37:58,807 --> 00:38:00,877 l'm very impressed by your optimism. 467 00:38:02,727 --> 00:38:06,037 Solitons are rare, not easily produced. 468 00:38:07,087 --> 00:38:13,083 The boat must gain enough speed to form a sizeable bow wave then come to a sudden stop. 469 00:38:13,727 --> 00:38:16,321 Hopefully that'll release a soliton. 470 00:38:18,567 --> 00:38:21,400 lf it does, l'm going to chase it, just like Russell, 471 00:38:21,447 --> 00:38:24,644 only l'll be racing it on foot, not on horseback. 472 00:38:26,607 --> 00:38:29,883 l've run up mountains, and l've run a few marathons. 473 00:38:32,047 --> 00:38:35,642 But l've never run against a wave before. l'm not sure l'm going to have to. 474 00:38:41,887 --> 00:38:43,206 Oh, my God! 475 00:39:12,887 --> 00:39:17,358 l beat it over a few hundred metres, but it's still going. 476 00:39:18,887 --> 00:39:22,846 And l'm not going to be able to keep going as long as that wave. 477 00:39:22,887 --> 00:39:24,605 (Cheering) 478 00:39:26,687 --> 00:39:33,035 John Scott Russell designed special boats to ride his wave at high speed along canals. 479 00:39:34,167 --> 00:39:39,400 But sadly, most people preferred a new form of transport - the railway. 480 00:39:40,087 --> 00:39:43,682 Russell waved goodbye to his bright idea. 481 00:39:45,327 --> 00:39:49,400 True to its nature, though, the soliton wasn't finished. 482 00:39:51,287 --> 00:39:59,638 Today, the solitary waves first seen on this canal aren't only found in water, they travel as light. 483 00:40:06,127 --> 00:40:11,042 Scientists have created soliton waves from tiny pulses of light. 484 00:40:12,687 --> 00:40:15,804 Fired down the next generation of fibre-optic cables, 485 00:40:16,247 --> 00:40:21,196 these self-sustaining waves can carry communications for thousands of miles, 486 00:40:21,927 --> 00:40:24,521 travelling on endlessly between continents, 487 00:40:25,687 --> 00:40:29,999 just as John Scott Russell's wave ran on out of sight of me. 488 00:40:31,327 --> 00:40:34,000 - So his day has come. - His day has finally come. 489 00:40:34,047 --> 00:40:37,164 And if you were to meet him now, what would you say to him? 490 00:40:37,207 --> 00:40:41,803 l would tell him that his idea has really come of age and everybody talks about him, 491 00:40:41,847 --> 00:40:43,838 everybody talks about the soliton. 492 00:40:43,887 --> 00:40:47,277 lt's a really big thing in science, so he'd be delighted, l think. 493 00:40:47,327 --> 00:40:49,318 - Satisfied scientist? - Yes. 494 00:41:02,327 --> 00:41:07,321 On a journey around our estuaries, we've arrived at the mighty Severn. 495 00:41:08,687 --> 00:41:14,637 Here the Atlantic Ocean surges in to collide with Britain's longest river. 496 00:41:15,607 --> 00:41:22,399 The Severn Estuary has a staggering rise of tidal water, some 1 5 metres in all. 497 00:41:26,607 --> 00:41:29,644 The sea swirls in strange patterns here. 498 00:41:32,367 --> 00:41:39,125 lts currents would wash the bodies of wrecked sailors to the same spot again and again - 499 00:41:39,847 --> 00:41:41,838 the village of Brean. 500 00:41:50,327 --> 00:41:54,684 Those unknown souls delivered to the doorstep of Brean needed burial, 501 00:41:56,607 --> 00:41:58,802 a sorrowful ritual remembered in song. 502 00:42:00,127 --> 00:42:04,917 Folk singer and storyteller June Tabor recalls The Brean Lament. 503 00:42:06,807 --> 00:42:11,483 The first thing that strikes you about being here...it's timeless. 504 00:42:12,567 --> 00:42:15,877 lt could be any time between now and 200 years ago. 505 00:42:17,367 --> 00:42:22,521 And the old timbers of this ship going nowhere ever again. 506 00:42:23,367 --> 00:42:27,519 The men who were on this ship, did they survive? 507 00:42:32,727 --> 00:42:37,437 The waters, they washed them ashore 508 00:42:37,487 --> 00:42:39,478 Ashore 509 00:42:40,647 --> 00:42:46,517 And they never will sail the seas no more 510 00:42:47,847 --> 00:42:53,205 We led them along by the churchyard wall 511 00:42:54,927 --> 00:43:00,445 And all in a row we buried them all 512 00:43:03,087 --> 00:43:05,078 The song The Brean Lament 513 00:43:05,127 --> 00:43:10,360 describes what happened quite commonly along this coast 514 00:43:10,407 --> 00:43:12,841 when bodies were washed up. 515 00:43:13,487 --> 00:43:16,479 You have to give them burial 516 00:43:17,967 --> 00:43:22,677 but not in the main churchyard, in a separate sailors' graveyard. 517 00:43:26,207 --> 00:43:29,517 lt was quite strongly believed along this stretch of coast 518 00:43:29,567 --> 00:43:34,402 that the sea might decide to reclaim their bodies as its own. 519 00:43:35,367 --> 00:43:40,361 They didn't want the dead of the village being taken at the same time. 520 00:43:42,847 --> 00:43:46,681 Possibly as a way of appeasing the sea, 521 00:43:47,887 --> 00:43:52,642 the sailors' boots were buried below the tide line, 522 00:43:53,447 --> 00:43:55,358 so the sea would have something to take. 523 00:43:58,127 --> 00:44:03,724 We led them along by the churchyard wall 524 00:44:05,407 --> 00:44:11,482 Where all in a row we buried them all 525 00:44:14,247 --> 00:44:16,238 But their boots 526 00:44:17,367 --> 00:44:23,237 We buried below the tide 527 00:44:25,447 --> 00:44:31,044 On Severnside 528 00:44:43,327 --> 00:44:47,115 NlCK: The Severn Estuary used to pose a fearsome challenge 529 00:44:47,167 --> 00:44:50,159 on any journey between England and Wales. 530 00:44:51,647 --> 00:44:56,516 The two countries were divided by this massive tear in our coastline. 531 00:44:58,487 --> 00:45:01,365 Avoiding it meant a diversion deep inland. 532 00:45:02,687 --> 00:45:07,238 Even so, only hardy travellers would brave the deadly waters. 533 00:45:14,607 --> 00:45:18,759 Today, a concrete solution spans this vast channel. 534 00:45:20,767 --> 00:45:27,923 But conquering the Severn was a bold venture fraught with peril, as Mark is about to discover. 535 00:45:30,327 --> 00:45:33,046 Dashing over the estuary from Wales to England, 536 00:45:33,087 --> 00:45:38,639 commuters take the elegant crossings their lives depend on for granted. 537 00:45:40,047 --> 00:45:43,357 But imagine a world before this bridge was possible - 538 00:45:43,847 --> 00:45:45,838 a world without steel cables, 539 00:45:46,807 --> 00:45:48,798 without reinforced concrete, 540 00:45:49,487 --> 00:45:52,240 when the sea reigned supreme. 541 00:45:52,927 --> 00:45:57,921 That was the challenge faced by the Victorians to cross the River Severn. 542 00:46:02,687 --> 00:46:09,638 The formidable collision of river and sea facing the early engineers can still be experienced. 543 00:46:11,927 --> 00:46:16,398 lt's one of the most dangerous seaways in the world, and l'm just a little bit excited. 544 00:46:19,087 --> 00:46:24,605 The Severn Area Rescue Association is going to pit me against the ebb tide. 545 00:46:26,687 --> 00:46:27,676 Cast off! 546 00:46:29,247 --> 00:46:32,159 The power of the tide here is just extraordinary! 547 00:46:38,767 --> 00:46:41,281 When the tide goes out, it's like a maelstrom. 548 00:46:43,647 --> 00:46:51,042 The waters were an immense challenge, but by the1 840s, crossing the river by boat was old hat. 549 00:46:55,047 --> 00:46:59,086 An irresistible new force was spreading across Britain - the railways. 550 00:47:00,207 --> 00:47:05,406 Come hell or high water, estuaries weren't going to stand in the way of progress. 551 00:47:09,727 --> 00:47:14,755 The great Victorian engineer lsambard Kingdom Brunel is a hero of mine. 552 00:47:15,527 --> 00:47:19,759 He'd already managed to cross the Avon Gorge with a mighty suspension bridge. 553 00:47:19,807 --> 00:47:24,437 When his railway came to Bristol, he wanted to cross into South Wales 554 00:47:24,487 --> 00:47:27,081 and planned an even bigger suspension bridge. 555 00:47:27,127 --> 00:47:29,118 Here are the preliminary sketches. 556 00:47:30,287 --> 00:47:37,762 The biggest problem was the sheer scale of the span that Brunel required - over 1,000 feet. 557 00:47:40,247 --> 00:47:46,880 He left a little note in his notebook which says, ''ls 1 ,1 00 feet practicable?'' 558 00:47:50,327 --> 00:47:52,318 Brunel's bridge was never built. 559 00:47:53,047 --> 00:47:57,916 But if taking trains over the water defeated the best brain of the age, 560 00:47:58,687 --> 00:48:00,678 how about going underneath? 561 00:48:02,247 --> 00:48:04,238 A tunnel, was that the answer? 562 00:48:06,327 --> 00:48:13,677 Digging deep to create a railway under the water, this was very bold, big thinking. 563 00:48:14,927 --> 00:48:19,045 This is one of the original drawings of the tunnel from around 1 887, 564 00:48:19,527 --> 00:48:22,917 and you can see how the track comes down 565 00:48:22,967 --> 00:48:26,960 underneath the deepest part of the Bristol Channel here in The Shoots, 566 00:48:27,007 --> 00:48:29,726 then gradually up to the Welsh side. 567 00:48:30,447 --> 00:48:33,996 So what we've got here is around seven miles of railway track. 568 00:48:35,967 --> 00:48:42,406 That passage under the estuary is now a vital link between England and Wales, 569 00:48:43,087 --> 00:48:46,204 carrying over 250 trains a day. 570 00:48:48,607 --> 00:48:55,524 Passengers are oblivious to a catastrophe that nearly sank the tunnel before the first train ran 571 00:48:56,967 --> 00:48:59,925 and is a problem that still lurks below. 572 00:49:03,487 --> 00:49:04,966 So here we go. 573 00:49:06,287 --> 00:49:11,919 l've been granted access to a shadowy waterworld few get to see. 574 00:49:14,007 --> 00:49:17,795 lt's great, we're just coming into the cutting, the portal's ahead 575 00:49:17,847 --> 00:49:20,281 and we're about to go under the sea. 576 00:49:24,527 --> 00:49:28,520 Ahh! Wahey! lsn't that fantastic? 577 00:49:30,807 --> 00:49:33,685 We're heading for the deepest point in the tunnel. 578 00:49:37,047 --> 00:49:42,565 Just 50 feet above us, millions of gallons of water are swirling around, 579 00:49:43,127 --> 00:49:47,006 the river Severn and the sea are in full flow. 580 00:49:47,047 --> 00:49:49,880 Keeping the water out here is hard enough, 581 00:49:49,927 --> 00:49:53,283 but can you imagine if there was a flood down here? 582 00:49:55,967 --> 00:50:02,076 With an estuary hanging over their heads, engineers knew there'd be seepage of seawater 583 00:50:03,287 --> 00:50:07,280 but it was freshwater that nearly drowned the project. 584 00:50:09,607 --> 00:50:12,075 Nobody expected this. 585 00:50:13,087 --> 00:50:18,115 A raging torrent - they'd broken through to an underground spring. 586 00:50:19,647 --> 00:50:24,880 ln October 1 879, water began to pour into the tunnel. 587 00:50:26,247 --> 00:50:28,238 The workers fled for their lives. 588 00:50:31,287 --> 00:50:35,360 The disaster struck when a shaft dug on the Welsh coast 589 00:50:35,967 --> 00:50:40,085 cut into an underground river deep below the surface. 590 00:50:42,807 --> 00:50:48,677 For four years, the engineers made desperate attempts to block the freshwater spring, 591 00:50:49,527 --> 00:50:52,280 but every effort proved futile. 592 00:50:55,207 --> 00:50:58,517 And it's been flooding in at this alarming rate ever since. 593 00:51:00,367 --> 00:51:04,280 lf they couldn't stop the spring water, they'd have to live with it. 594 00:51:07,007 --> 00:51:10,761 The only solution was pumps, massive ones like this, 595 00:51:10,807 --> 00:51:15,835 that pump the water out as fast as it comes in, right up to the surface. 596 00:51:18,807 --> 00:51:22,720 Leighton Jenkins helps keep the tracks dry today. 597 00:51:22,927 --> 00:51:25,839 So what would happen if the pumps actually failed? 598 00:51:25,887 --> 00:51:27,684 Every second counts. 599 00:51:27,727 --> 00:51:31,606 As soon as the pumps stop, we'd have to inform the control within ten minutes 600 00:51:31,647 --> 00:51:33,717 just to shut the tunnel itself, 601 00:51:33,767 --> 00:51:36,964 and within 20 minutes, we've water coming up through the tracks. 602 00:51:37,007 --> 00:51:38,918 Every second absolutely counts. 603 00:51:38,967 --> 00:51:40,958 MARK: But have they yet failed? 604 00:51:41,007 --> 00:51:45,000 No, not as far as l know, no. Not while l'm on the shift, anyway. (Laughs) 605 00:51:46,767 --> 00:51:53,115 The railways had proved irresistible, with rival Victorian companies vying for routes. 606 00:51:53,967 --> 00:51:58,085 By the time it was finished, the tunnel already had a competitor. 607 00:52:03,327 --> 00:52:07,798 ln 1 879, trains had started to roll over the estuary. 608 00:52:09,207 --> 00:52:13,280 But the bridge's sturdy uprights, always an obstacle to shipping, 609 00:52:13,967 --> 00:52:16,083 would ultimately prove its downfall. 610 00:52:19,127 --> 00:52:20,765 Do you see? 611 00:52:20,807 --> 00:52:26,120 That's a tower where a railway bridge once crossed the Severn Estuary. 612 00:52:26,687 --> 00:52:31,841 l've got a photograph that shows the stanchions marching across the river. 613 00:52:32,487 --> 00:52:34,478 lt's now totally destroyed. 614 00:52:37,727 --> 00:52:42,005 The raging waters where river and sea smash together 615 00:52:42,567 --> 00:52:45,764 would deliver a fatal blow to the rail bridge. 616 00:52:49,487 --> 00:52:54,197 ln October 1 960, the Arkendale, carrying oil, 617 00:52:54,927 --> 00:52:57,521 and the Wastdale, laden with petrol, 618 00:52:58,367 --> 00:53:01,279 were heading for a combustible collision. 619 00:53:02,447 --> 00:53:05,439 The Arkendale was carried in by the surging tide. 620 00:53:07,727 --> 00:53:15,077 That powerful current would drive it into the Wastdale on a foggy night at Sharpness Docks. 621 00:53:16,447 --> 00:53:18,438 As Alan Hayward knows. 622 00:53:19,407 --> 00:53:22,797 They were coming upriver, intending to come into the docks here, 623 00:53:22,847 --> 00:53:24,917 but they were accidently swept past. 624 00:53:26,087 --> 00:53:29,796 And then they collided and became, in effect, stuck together. 625 00:53:31,567 --> 00:53:33,558 Disabled ships in thick fog, 626 00:53:34,127 --> 00:53:39,963 carrying 600 tonnes of inflammable cargo at the mercy of a swirling sea, 627 00:53:40,687 --> 00:53:42,678 propelled them to disaster. 628 00:53:44,767 --> 00:53:47,406 They were desperate to separate from each other, 629 00:53:48,047 --> 00:53:51,801 fighting by steering in different directions but it just didn't work, 630 00:53:51,847 --> 00:53:56,443 and they only had about four minutes before they would reach the railway bridge. 631 00:53:58,167 --> 00:54:01,284 The rail bridge across the Severn loomed out of the fog. 632 00:54:02,167 --> 00:54:06,922 A collision with the ships carrying oil and petrol was now inevitable. 633 00:54:12,847 --> 00:54:17,443 A lot of sparks would have been created which ignited the petrol in one of the vessels. 634 00:54:20,527 --> 00:54:25,396 The fuel, of course, spilt out over the river, so the whole river became a mass of flame. 635 00:54:29,087 --> 00:54:32,284 First mate Percy Simmonds was aboard one of the tankers. 636 00:54:33,367 --> 00:54:35,722 His son Chris was 1 3 at the time. 637 00:54:35,767 --> 00:54:38,884 CHRlS: l try to imagine that night and what he was going through. 638 00:54:38,927 --> 00:54:41,077 lt must have been just terrible with the flames. 639 00:54:41,967 --> 00:54:45,755 l'm just sure he was determined to make it across this river somehow 640 00:54:46,927 --> 00:54:48,918 and make it back to us. 641 00:54:50,047 --> 00:54:54,643 Daylight and a low tide revealed wrecks of the fuel tankers 642 00:54:54,687 --> 00:54:56,678 smouldering on a sandbank. 643 00:54:57,887 --> 00:54:59,878 Soon the first body was found. 644 00:55:01,247 --> 00:55:03,442 They identified the body there. 645 00:55:03,487 --> 00:55:05,478 They let Mum know... 646 00:55:06,487 --> 00:55:08,921 ..that, yeah, it was definitely Perce. 647 00:55:08,967 --> 00:55:14,439 Chris's father Percy died along with four others on that terrible evening. 648 00:55:15,327 --> 00:55:19,923 The damaged bridge was too expensive to repair, it was demolished. 649 00:55:20,847 --> 00:55:26,444 But each day when the tide recedes, scars of tragedy are revealed. 650 00:55:27,127 --> 00:55:30,642 CHRlS: Out there, of course, are two hulks buried now in the sands. 651 00:55:30,687 --> 00:55:34,680 They've been washed over by countless tides, but they're still there. 652 00:55:34,727 --> 00:55:36,718 They're there as monuments, 653 00:55:36,767 --> 00:55:38,883 they're here as a reminder to all of us. 654 00:55:42,927 --> 00:55:48,797 lt's immensely humbling to be next to such a vast body of brooding water, 655 00:55:49,527 --> 00:55:52,599 even on a calm day like this. 656 00:55:53,167 --> 00:55:58,799 One can feel the power where rivers and sea collide. 657 00:56:10,327 --> 00:56:15,959 Britain's mighty estuaries have pushed engineers to breaking point and beyond. 658 00:56:18,327 --> 00:56:24,641 ln Scotland, there's a salty graveyard of overreaching ambition - the Tay. 659 00:56:29,567 --> 00:56:35,676 This immense river disgorges more water into the sea than the Thames and Severn combined. 660 00:56:36,967 --> 00:56:41,245 ln the shadow of today's rail crossing is a spine of stumps - 661 00:56:43,647 --> 00:56:46,525 the footings of the first Tay Bridge. 662 00:56:48,287 --> 00:56:53,236 On a stormy night in December 1 879, it collapsed. 663 00:56:54,127 --> 00:56:56,118 60 passengers died... 664 00:56:59,567 --> 00:57:04,243 ..and so did the myth of infallible Victorian engineers. 665 00:57:06,527 --> 00:57:12,796 The blame was put on designer Thomas Bouch, lax maintenance and poor ironwork. 666 00:57:16,607 --> 00:57:20,122 Hard lessons learned just down the coast on the Firth of Forth. 667 00:57:27,087 --> 00:57:29,396 Following the disaster at the Tay Bridge, 668 00:57:29,447 --> 00:57:33,156 that designer's plans for this crossing were thrown out. 669 00:57:34,047 --> 00:57:39,201 The Forth Rail Bridge was beefed up into a massive cantilevered skeleton, 670 00:57:39,727 --> 00:57:42,241 built not of iron, but steel. 671 00:57:43,807 --> 00:57:47,641 This bridge is really a memorial, a masterpiece in steel 672 00:57:47,687 --> 00:57:52,044 to the poor souls who lost their lives in the Tay Bridge tragedy. 673 00:57:58,407 --> 00:58:02,082 Surging waters urge us on to fresh endeavours. 674 00:58:04,127 --> 00:58:10,316 And we're not alone in finding creature comforts around the fringes of our great seaways. 675 00:58:12,447 --> 00:58:17,760 The tide brings in the bounty that makes our estuaries brim with vitality. 676 00:58:26,167 --> 00:58:29,921 Safe havens that offer boundless prospects. 677 00:58:31,447 --> 00:58:38,558 Where rivers collide with the sea, our coast comes alive and opportunity awaits.