0:00:07 > 0:00:10Coast is home.
0:00:12 > 0:00:17We're back to explore the most endlessly fascinating shoreline
0:00:17 > 0:00:19in the world - our own!
0:00:21 > 0:00:26The quest to discover surprising, secret stories
0:00:26 > 0:00:28from around the British Isles continues.
0:00:33 > 0:00:36This is Coast.
0:01:07 > 0:01:08For as long as we've gazed
0:01:08 > 0:01:10from our island shores over the seas,
0:01:10 > 0:01:13we've struggled to solve
0:01:13 > 0:01:15the mystery of our tides.
0:01:15 > 0:01:20Twice a day, like the chest of a sleeping giant,
0:01:20 > 0:01:22the sea heaves up and down,
0:01:22 > 0:01:24re-drawing the shape of our island home.
0:01:24 > 0:01:29The effect of the two tides varies around the coast.
0:01:29 > 0:01:30In the Bristol Channel,
0:01:30 > 0:01:35we have one of the greatest surges of water in the world.
0:01:35 > 0:01:39It creates the remarkable Severn Bore.
0:01:39 > 0:01:42Over in East Anglia in the south-east corner of England,
0:01:42 > 0:01:45the tides are relatively weak.
0:01:45 > 0:01:48Down here on the south coast, the opposite is true,
0:01:48 > 0:01:51because the tides get forced up and down the English Channel
0:01:51 > 0:01:56around a promontory called Portland Bill.
0:01:56 > 0:01:59You get huge standing waves there. It's really scary.
0:02:02 > 0:02:05Why does the sea behave so differently around our coast?
0:02:05 > 0:02:10We're here to explore The Riddle Of The Tides.
0:02:12 > 0:02:17My tidal odyssey takes me to the North West,
0:02:17 > 0:02:19and a city that sits by the sea.
0:02:19 > 0:02:23In Liverpool, I'm on the trail of a forgotten genius,
0:02:23 > 0:02:26who made a machine to calculate the tides anywhere, anytime.
0:02:29 > 0:02:34Look at that, lots of brass, cast iron, steel axles,
0:02:34 > 0:02:36absolutely stunning, isn't it?
0:02:36 > 0:02:41In the balmy south, there's an island that puts on a spectacular
0:02:41 > 0:02:43tidal show.
0:02:43 > 0:02:45At a fortress that floods twice a day,
0:02:45 > 0:02:49Miranda is mega-rockpooling in Jersey.
0:02:49 > 0:02:53This has to be the weirdest thing I've ever done in a rock pool.
0:02:53 > 0:02:56And there's actually a little brown shrimp just sitting on my hand,
0:02:56 > 0:02:58feeding off little bits of skin.
0:02:58 > 0:02:59On the east coast,
0:02:59 > 0:03:03we explore the ebb and flow
0:03:03 > 0:03:06that drove beach fashion at Britain's first resort.
0:03:06 > 0:03:10Scarborough is where we hide at low tide,
0:03:10 > 0:03:15and the Victorian bathing hut rides again, for Lady Tessa.
0:03:16 > 0:03:17- Has the horse had enough?- Yeah.
0:03:17 > 0:03:20- I don't blame her. Do you?- No.
0:03:21 > 0:03:26But my journey begins on tidal rapids. The Menai Strait...
0:03:29 > 0:03:32..a narrow ribbon of wild water.
0:03:38 > 0:03:43Mariners have always been at the mercy of the tides.
0:03:43 > 0:03:47Trying to master those turbulent waters
0:03:47 > 0:03:50was a great voyage of discovery.
0:03:52 > 0:03:58I'm setting sail on this 19th-century-style schooner...
0:03:58 > 0:04:00Shall we put it up, Scott?
0:04:00 > 0:04:01Yes, go for it.
0:04:01 > 0:04:07..to see how salty seadogs began to tackle the riddle of the tides.
0:04:07 > 0:04:09Good work out, isn't it? Earning a living.
0:04:09 > 0:04:12It's all hands on deck as we rush to set sail
0:04:12 > 0:04:15before the tide turns against us.
0:04:15 > 0:04:18Proper old ropes that takes the skin off your hands.
0:04:24 > 0:04:29A tricky passage awaits along some of Britain's most treacherous water.
0:04:29 > 0:04:32Navigating the Menai Strait isn't for the fainthearted.
0:04:32 > 0:04:36We're racing to make it through The Swellies -
0:04:36 > 0:04:40the tidal surge around the island of Anglesey.
0:04:40 > 0:04:44Any misjudgement of the tides here could wreck the boat on jagged rocks.
0:04:44 > 0:04:48It's a real worry for the skipper, Scott Metcalfe.
0:04:48 > 0:04:51Quite a few people have come to grief.
0:04:51 > 0:04:54There's a lot of rocks around here, there's rocks on this side,
0:04:54 > 0:04:57and certainly there's rocks on the other side,
0:04:57 > 0:04:59the Cribbin Rock, which is quite a nasty one.
0:04:59 > 0:05:00If you get the timing wrong
0:05:00 > 0:05:01you can get swept onto
0:05:01 > 0:05:03one of the rocks, basically.
0:05:03 > 0:05:06And this is a, you know, a historic vessel.
0:05:06 > 0:05:10How important were tides back in the days before motors?
0:05:10 > 0:05:12Very, very important.
0:05:12 > 0:05:14I don't know if you can see those two white posts,
0:05:14 > 0:05:17we should have those basically in line.
0:05:17 > 0:05:19So, you line the two white posts up,
0:05:19 > 0:05:23steer for the posts, and that gets you through the deeper channel.
0:05:23 > 0:05:25People talk about The Swellies
0:05:25 > 0:05:27as if it's some kind of white-knuckle fairground ride.
0:05:27 > 0:05:28What are The Swellies?
0:05:28 > 0:05:32That's just this stretch of water between the two bridges, basically.
0:05:32 > 0:05:37It is the fastest flowing part. This is the most treacherous part.
0:05:37 > 0:05:43Scott makes sure to navigate The Swellies at slack water -
0:05:43 > 0:05:47the brief period when the tidal flow is weakest.
0:05:47 > 0:05:52For sailors, reading the mood of the sea is a matter of life and death.
0:05:53 > 0:05:55Since the earliest times,
0:05:55 > 0:05:58mariners have known that the moon drives the tides,
0:05:58 > 0:06:01but how, exactly?
0:06:01 > 0:06:04And why are there two tides a day?
0:06:04 > 0:06:10Sailing with me is Tom Rippeth from Bangor University.
0:06:10 > 0:06:11Tom, can you explain to me
0:06:11 > 0:06:14why it is that we get two tides every 24 hours.
0:06:14 > 0:06:16We've got a simple model, here, Nick.
0:06:16 > 0:06:18If you'd just like to hold that.
0:06:18 > 0:06:19Yes.
0:06:19 > 0:06:22This is obviously the earth, and then here we have the moon
0:06:22 > 0:06:24and, erm, the earth and moon,
0:06:24 > 0:06:27basically, orbit around each other in space,
0:06:27 > 0:06:29and erm there's two forces acting, really.
0:06:29 > 0:06:33There's one force which is the moon's gravitational pull,
0:06:33 > 0:06:35and another force which is the centrifugal force,
0:06:35 > 0:06:39which is pulling the water away from the planet.
0:06:39 > 0:06:44The earth's motion and the moon's gravity make the tides.
0:06:44 > 0:06:48To see how, imagine our planet completely covered in water.
0:06:48 > 0:06:52One bulge in the sea is caused by the moon's pull.
0:06:52 > 0:06:57There's an opposite bulge because water gets pushed out
0:06:57 > 0:07:01by centrifugal force, as the earth whizzes through space.
0:07:02 > 0:07:08The earth also rotates, once every 24 hours.
0:07:10 > 0:07:13Measure the sea level at a single point
0:07:13 > 0:07:18and it rises as the earth spins, and then falls again,
0:07:18 > 0:07:26and sea level rises again 12 hours later, so two high tides a day.
0:07:26 > 0:07:29But our world isn't completely submerged,
0:07:29 > 0:07:33the shape of the coastline and cliffs on the seabed,
0:07:33 > 0:07:35like the continental shelf,
0:07:35 > 0:07:40disrupt the flow of water, changing the height of our tides.
0:07:40 > 0:07:42Our tides go up and down at the edge of the continental shelf,
0:07:42 > 0:07:45and that generates tidal waves.
0:07:45 > 0:07:48So, we're not talking about a gradual rising
0:07:48 > 0:07:50and falling of water every, what, six hours, roughly?
0:07:50 > 0:07:52Absolutely not. We're talking about waves
0:07:52 > 0:07:56which will travel down one coastline and travel up another coastline,
0:07:56 > 0:07:59so, for instance, down the east coast of England,
0:07:59 > 0:08:01we'll see big changes in the height of the tide,
0:08:01 > 0:08:04but also in the timing of the tide,
0:08:04 > 0:08:06so you might have low water in the north,
0:08:06 > 0:08:08and you might have high water in the south.
0:08:08 > 0:08:10So, our tides aren't simple.
0:08:10 > 0:08:13They travel in massive waves,
0:08:13 > 0:08:18which makes it hard to predict the sea-level.
0:08:18 > 0:08:22Tom's wave tank shows how the tide behaves differently,
0:08:22 > 0:08:24depending where you are.
0:08:24 > 0:08:27Here we've just put three examples on the Irish Sea.
0:08:27 > 0:08:30We've got Liverpool, here, which has very large tides,
0:08:30 > 0:08:33and if you move elsewhere in the Irish sea, we actually see
0:08:33 > 0:08:35places where it's high water at Liverpool
0:08:35 > 0:08:36and it can be low water elsewhere.
0:08:36 > 0:08:39So, you can have high water at different times
0:08:39 > 0:08:41- in different parts of the coast? - That's right.
0:08:41 > 0:08:44- It's a very complex system, isn't it? - Absolutely, very complex.
0:08:44 > 0:08:50Tides are further complicated by our craggy shoreline,
0:08:50 > 0:08:53which makes predicting them very tricky.
0:08:53 > 0:08:57But later I'll discover a remarkable machine,
0:08:57 > 0:09:00created to crack the puzzle.
0:09:03 > 0:09:07But while some probe the mystery of the tides, others work with them.
0:09:07 > 0:09:10Along the southern shore of England,
0:09:10 > 0:09:15the Atlantic surge is funnelled between Britain and France.
0:09:15 > 0:09:20The sea's ebb and flow is the clock for these coastal folk.
0:09:20 > 0:09:24At Hastings, the high tide is the fishermen's friend,
0:09:24 > 0:09:27allowing them to float their boats off the beach.
0:09:27 > 0:09:30But it can mean an early start.
0:09:38 > 0:09:42Further west, the way the water sloshes around the Isle of Wight
0:09:42 > 0:09:44into the Solent
0:09:44 > 0:09:47creates four high tides each day,
0:09:47 > 0:09:49double the normal number,
0:09:49 > 0:09:53a challenge if you're messing around in boats.
0:09:53 > 0:09:57All around the shore, tidal life runs on local knowledge,
0:09:57 > 0:09:59like here at Bantham.
0:10:04 > 0:10:10The town is home to marine biologist and mum Maya Plass.
0:10:10 > 0:10:14Maya makes the sea work for her.
0:10:14 > 0:10:17This morning I've got to get my daughter Niamh to school.
0:10:17 > 0:10:19Did you brush your teeth yet this morning?
0:10:19 > 0:10:22Most parents have to check traffic reports in the morning,
0:10:22 > 0:10:23but for me, I check the tide tables.
0:10:23 > 0:10:26The tide controls my life here.
0:10:28 > 0:10:31Unfortunately, this morning, I've got to take Niamh by van,
0:10:31 > 0:10:34but this evening, hopefully, I'll be able to pick her up by kayak
0:10:34 > 0:10:36on the high tide.
0:10:38 > 0:10:43For Maya, as for most parents, the school run is a frantic rush.
0:10:43 > 0:10:45- Sorry, we're a bit late. - No, you're fine, not a problem.
0:10:45 > 0:10:47But she's also rushing for another reason -
0:10:47 > 0:10:50she's racing against the tide.
0:10:50 > 0:10:53I've got to catch that tidal road.
0:10:53 > 0:10:55On the high tide this road is completely covered,
0:10:55 > 0:10:58and there will be stretches that will be completely submerged.
0:10:58 > 0:11:02You often find people stranded on this bit of road.
0:11:02 > 0:11:04Maya's got to get a move on -
0:11:04 > 0:11:06while it's still low tide,
0:11:06 > 0:11:12this marine biologist mum can free-dive to get her family dinner.
0:11:12 > 0:11:16I'm going to hop in and hopefully find a spider crab.
0:11:19 > 0:11:24Shallow water means Maya can reach the bottom with one gulp of air.
0:11:32 > 0:11:36I've got two females here.
0:11:36 > 0:11:38You can tell they're females
0:11:38 > 0:11:41because they've got really small claws here.
0:11:41 > 0:11:44They've got this big rounded area that's under there
0:11:44 > 0:11:46that she'll keep all her eggs,
0:11:46 > 0:11:47but we don't want the females.
0:11:47 > 0:11:50We want the males - the ones with the nice big juicy claws.
0:12:03 > 0:12:06Look at this, he's amazing.
0:12:06 > 0:12:08It's a lovely big male.
0:12:08 > 0:12:11Look at the amazing size of his claws!
0:12:11 > 0:12:13Loads of meat in there.
0:12:13 > 0:12:16This one's definitely going to be for supper.
0:12:17 > 0:12:21It's time to go and collect Niamh now.
0:12:21 > 0:12:24If she times it right, Maya can kayak in with the tide...
0:12:24 > 0:12:27The tide time changes every day...
0:12:27 > 0:12:29..collect Niamh from school
0:12:29 > 0:12:32..so, the teachers are really flexible to the fact that sometimes
0:12:32 > 0:12:35I am a little bit late.
0:12:35 > 0:12:38And, as the tide turns, get a free ride back.
0:12:45 > 0:12:49- Look down here, can you see those cars down there?- Yeah.
0:12:49 > 0:12:54They can't actually get across on this road cos the water's too deep.
0:12:54 > 0:12:57But we can. How cool is that?
0:12:57 > 0:13:03This morning, she drove along this road. Now, it's become a boat trip.
0:13:03 > 0:13:08And soon the tide will turn again, right around our shores.
0:13:15 > 0:13:22The routine of coastal folk revolves around the ebb and flow of the sea.
0:13:22 > 0:13:29It reshapes their world and opens up new possibilities.
0:13:29 > 0:13:32Like on this beach in Cardigan Bay,
0:13:32 > 0:13:36on the west coast of Wales at Poppit Sands.
0:13:40 > 0:13:44Mark's on the trail of some long dead monks
0:13:44 > 0:13:47and the cunning trap they left behind.
0:13:49 > 0:13:55Even in the drizzle, Poppit Sands in Wales is a popular beach.
0:13:55 > 0:13:58A great place to sit back and take in the view.
0:13:58 > 0:14:03But sometimes we can't see what's under our noses.
0:14:05 > 0:14:07We all like to look out to see,
0:14:07 > 0:14:09and we know the history of the sea,
0:14:09 > 0:14:11but there's often hidden histories
0:14:11 > 0:14:13underneath the sea.
0:14:16 > 0:14:18For hundreds of years,
0:14:18 > 0:14:22these waters were hiding an Atlantis-like structure,
0:14:22 > 0:14:26best seen from up high when the tide is low.
0:14:29 > 0:14:32A few years ago this remarkable picture was taken.
0:14:32 > 0:14:37We're standing just there, but here is this extraordinary
0:14:37 > 0:14:38v-shaped feature,
0:14:38 > 0:14:42which the archaeologists interpreted as a medieval fish trap,
0:14:42 > 0:14:46capable of bagging literally thousands of fish.
0:14:48 > 0:14:53The aerial view revealed a submerged stone structure -
0:14:53 > 0:14:59a man-made pen to trap fish at low tide.
0:14:59 > 0:15:03It's around 900 years old.
0:15:03 > 0:15:08How did something so big become forgotten?
0:15:08 > 0:15:12I'm here with local diver Ziggy Otto.
0:15:12 > 0:15:13- Hi.- Hello.
0:15:17 > 0:15:20Why did it take so long for us archaeologists to find this?
0:15:20 > 0:15:23I mean, it's so enormous.
0:15:23 > 0:15:25Because it's covered, even at low tide,
0:15:25 > 0:15:28because sea-level has risen, and I believe by,
0:15:28 > 0:15:30and this is an estimate of,
0:15:30 > 0:15:33a metre over the past thousand years,
0:15:33 > 0:15:34so, once upon a time
0:15:34 > 0:15:36this fish trap was inter tidal,
0:15:36 > 0:15:38exposed at low tide.
0:15:38 > 0:15:39How did it actually work?
0:15:39 > 0:15:44You have a wide opening that was possibly even extended by nets
0:15:44 > 0:15:48even further to corral the fish into the trap,
0:15:48 > 0:15:51possible close the trap and let the tide go out and pick up your fish.
0:15:51 > 0:15:53A very, very efficient system.
0:15:53 > 0:15:56You'd come and pick up the fish who were thrashing around in the sand.
0:15:56 > 0:15:57Absolutely.
0:15:59 > 0:16:04This man-made rock pool is over 800 feet long,
0:16:04 > 0:16:09painstakingly built from stones piled up by hand.
0:16:09 > 0:16:13An extraordinary achievement
0:16:13 > 0:16:16for the men who constructed it in the 12th century.
0:16:18 > 0:16:22In its heyday, this trap would be capable
0:16:22 > 0:16:24of catching thousands of fish,
0:16:24 > 0:16:28but who was mad enough to spend the money
0:16:28 > 0:16:32to build and maintain such a contraption?
0:16:35 > 0:16:40A bird's eye view, once again, gives us a clue.
0:16:40 > 0:16:44The long gardens, here at St Dogmaels,
0:16:44 > 0:16:46are unusually narrow -
0:16:46 > 0:16:51typical of the sort of plots farmed by medieval tenants,
0:16:51 > 0:16:55whose landlords lived just next-door.
0:16:59 > 0:17:03Those landlords were the original inhabitants of this,
0:17:03 > 0:17:07St Dogmaels Abbey, founded from France around 1120,
0:17:07 > 0:17:11and whose monks had to live on a diet of fish.
0:17:11 > 0:17:17The abbey's original community consisted of 13 monks,
0:17:17 > 0:17:24brought over from France by the Norman baron Robert fitz Martin.
0:17:26 > 0:17:32As historian Glen Johnson knows, being members of a Benedictine order
0:17:32 > 0:17:33their monastic rule banned red meat
0:17:33 > 0:17:37meaning they needed a large amount of fish.
0:17:37 > 0:17:41So, it was the only meat they could have as part of the diet.
0:17:41 > 0:17:43How often they ate meat, we don't know,
0:17:43 > 0:17:47but all of it would have been fish and the trap, then,
0:17:47 > 0:17:49obviously, would have been very valuable
0:17:49 > 0:17:51to making sure that they had a constant supply.
0:17:53 > 0:17:56The industrious monks in their monastery
0:17:56 > 0:17:59would have once dominated the landscape.
0:17:59 > 0:18:04But the tides of time were turning against them.
0:18:04 > 0:18:07It began with the black death, in 1349.
0:18:07 > 0:18:13What had been a full house of honest and obedient monks were decimated
0:18:13 > 0:18:17by the arrival of this disease, and the abbey, to be honest,
0:18:17 > 0:18:18never really recovered.
0:18:18 > 0:18:20In the end, it went the way of all flesh
0:18:20 > 0:18:23with Henry VIII, a man who liked to chop and change.
0:18:25 > 0:18:30In 1536, Henry VIII had ordered the dissolution of the monasteries.
0:18:32 > 0:18:35When Henry's men had finished at St Dogmaels,
0:18:35 > 0:18:37the abbey was ruined.
0:18:40 > 0:18:43Then the monk's fish trap was lost
0:18:43 > 0:18:46as the sea-level rose over the centuries.
0:18:46 > 0:18:51But one ecclesiastical influence did survive the passage of time.
0:18:54 > 0:18:58Seine fishing is now a Welsh tradition,
0:18:58 > 0:19:02but historians believe it was first brought over
0:19:02 > 0:19:05by the French monks from the River Seine.
0:19:07 > 0:19:11So, Cyril, you've been fishing on this river for how long?
0:19:11 > 0:19:1330 years.
0:19:13 > 0:19:14And you've presumably caught
0:19:14 > 0:19:16a fair few fish in those times.
0:19:16 > 0:19:18Oh, yes, I've caught a few in my time, yes.
0:19:18 > 0:19:20So, how does this process actually work?
0:19:20 > 0:19:23Well, there's a boat and a crew of four -
0:19:23 > 0:19:26the Captain and the three nets men.
0:19:26 > 0:19:29As you pull the net in, you pull in slowly.
0:19:29 > 0:19:31You can see it's like a little horseshoe
0:19:31 > 0:19:33So, the whole thing runs like a bag?
0:19:33 > 0:19:35Like a bag, yes. That's what it is.
0:19:35 > 0:19:36That's what a Seine net is.
0:19:36 > 0:19:38And you have to come in at low tide?
0:19:38 > 0:19:43Yes, well if you're fishing, you're on high water, the tide is in,
0:19:43 > 0:19:46you haven't got any beach to land the net, you know?
0:19:46 > 0:19:48This will be ten ft of water around here.
0:19:48 > 0:19:49You've got no room to stand.
0:19:49 > 0:19:53So, now they're pulling the bottom of the net in,
0:19:53 > 0:19:55and, yes, there's a fish in it.
0:19:55 > 0:19:56Where?
0:19:56 > 0:19:58There's a fish in the net.
0:19:58 > 0:19:59Going through the net a mullet it is...
0:19:59 > 0:20:01look it's still in the net
0:20:01 > 0:20:03I can see it, yes there it is
0:20:03 > 0:20:05That's a Sewin.
0:20:07 > 0:20:11Only a few miles from our medieval trap,
0:20:11 > 0:20:16but a thousand years later, tidal fishing lives on.
0:20:16 > 0:20:22The times have changed but our reliance on our tides has not.
0:20:28 > 0:20:31We're on a journey to work out the riddle of the tides,
0:20:31 > 0:20:36the mysterious endless ebb and flow around our coast,
0:20:36 > 0:20:39and the curious ways we've put it to use.
0:20:40 > 0:20:46Canny Yorkshire folk saw a money making opportunity at Scarborough.
0:20:48 > 0:20:54Some 300 years ago, the nation fell in love with sea-bathing,
0:20:54 > 0:20:56a craze that began here.
0:20:56 > 0:21:01But the town had to find a way of tempting refined gentlefolk
0:21:01 > 0:21:04down to the water, even at low tide.
0:21:04 > 0:21:06Tessa is here to discover
0:21:06 > 0:21:10how Scarborough made sea-bathing fashionable
0:21:12 > 0:21:15In the mid 1800s, the population here was booming.
0:21:15 > 0:21:18Visitors flooded in,
0:21:18 > 0:21:22and grand hotels were built to accommodate the crowds.
0:21:24 > 0:21:29By the time Victoria was on the throne, we'd gone bathing-mad.
0:21:31 > 0:21:32But for a town
0:21:32 > 0:21:33that was selling itself
0:21:33 > 0:21:35on a swim in the sea,
0:21:35 > 0:21:38sometimes there was a bit of a problem.
0:21:38 > 0:21:40Where is the sea?
0:21:40 > 0:21:45Low tide reveals a huge expanse of beach
0:21:45 > 0:21:48and takes the sea a long way out.
0:21:48 > 0:21:52For a prim and proper Victorian lady, frolicking across the sand
0:21:52 > 0:21:55in her undies to meet the sea was out of the question,
0:21:55 > 0:21:58so, in Scarborough, they came up with this -
0:21:58 > 0:22:02a modesty cabinet, a bathing machine
0:22:02 > 0:22:04in which a woman could shelter
0:22:04 > 0:22:07as she was wheeled out to meet the tide.
0:22:11 > 0:22:15The very first evidence of a bathing machine in Britain
0:22:15 > 0:22:20is this image from 1736, set right here in Scarborough.
0:22:21 > 0:22:24And to get a glimpse of one of these contraptions
0:22:24 > 0:22:28I'm meeting Karen Snowden from the Scarborough museum.
0:22:29 > 0:22:31Hidden at the back of her storeroom,
0:22:31 > 0:22:34there's a bathing machine that's survived,
0:22:34 > 0:22:36but only just.
0:22:36 > 0:22:38Here we are.
0:22:38 > 0:22:40It's seen better days, hasn't it?
0:22:40 > 0:22:42Yes, it has.
0:22:42 > 0:22:46It spent many decades as a garden shed in Scarborough.
0:22:46 > 0:22:48When does it date from, do you know?
0:22:48 > 0:22:49Probably about 1870.
0:22:51 > 0:22:56I think it's fair to say that this bathing machine is out of service.
0:22:56 > 0:22:59So, just to see just how the bathing belles would have used them,
0:22:59 > 0:23:01we're going to have to get a bit creative.
0:23:01 > 0:23:05A bathing machine probably hasn't been built in Britain
0:23:05 > 0:23:07for about 100 years,
0:23:07 > 0:23:11but perhaps that's because nobody's tried, until now.
0:23:23 > 0:23:25And here it is!
0:23:25 > 0:23:28Basically, a DIY shed on wheels.
0:23:28 > 0:23:30And, of course, we need an unflappable horse,
0:23:30 > 0:23:35so, there's Brooklyn with her very own stable boy.
0:23:35 > 0:23:37We also need a dipper,
0:23:37 > 0:23:41a woman to help our lady dip into the sea.
0:23:41 > 0:23:44Cue Karen from the museum.
0:23:44 > 0:23:49And now all we need is the Victorian lady to take a dip.
0:23:49 > 0:23:50That'll be me.
0:23:58 > 0:24:04- Well, Carol, we've got this picture here of how it once was.- Yeah.
0:24:04 > 0:24:06How do you reckon we're looking?
0:24:06 > 0:24:08Well, not bad. Quite a close match.
0:24:08 > 0:24:10- It is, isn't it?- Yeah.
0:24:10 > 0:24:14Why did people want to dip in icy waters?
0:24:14 > 0:24:18They thought it was good for their health, and the colder the better.
0:24:18 > 0:24:24The idea isn't exactly filling me with joy but it's time to beach test
0:24:24 > 0:24:26our 21st-century bathing machine.
0:24:26 > 0:24:28C'mon. Walk on!
0:24:33 > 0:24:38The ladies could get changed on the way to the sea
0:24:38 > 0:24:43so that they were never seen in their indecent bathing costume.
0:24:43 > 0:24:47As my dipper, what would you be doing, what's your main role?
0:24:47 > 0:24:49I'd help you change and then I'd help you into the sea,
0:24:49 > 0:24:53and if you were a little bit reluctant to go all the way under,
0:24:53 > 0:24:55- I'd shove you under. - Thanks for that, Karen.
0:24:57 > 0:25:00I feel like I should be going to a cocktail party in this outfit,
0:25:00 > 0:25:01not for a swim.
0:25:04 > 0:25:06- Has the horse had enough?- Yeah.
0:25:06 > 0:25:09- I don't blame her. Do you?- No.
0:25:10 > 0:25:13So I'm not to swim, am I, cos I don't know how to swim?
0:25:13 > 0:25:15No, you don't know how to swim. You just dunk.
0:25:15 > 0:25:17Are we going to wait for a big wave?
0:25:17 > 0:25:20Yeah, there's a couple of big ones coming up soon, let's go for them.
0:25:20 > 0:25:21OK, push me.
0:25:21 > 0:25:24SHE SCREAMS
0:25:25 > 0:25:27- Oh, a nice big one coming.- OK.
0:25:30 > 0:25:34In their modesty, Victorian ladies bathed out of sight,
0:25:34 > 0:25:38but by the early 20th century, the horses were pensioned off
0:25:38 > 0:25:41as women became bolder about showing themselves.
0:25:43 > 0:25:48At low tide, suddenly the beach was the place to be seen.
0:25:48 > 0:25:52As sunbathing took hold, women no longer hid away.
0:25:52 > 0:25:55Instead, they wanted costumes to show off their curves.
0:25:59 > 0:26:03By the early 20th century, costumes started to look more familiar.
0:26:03 > 0:26:05They were often hand-knitted with wool.
0:26:05 > 0:26:11Stylish on the beach, but wool is soggy and shapeless when wet.
0:26:11 > 0:26:16So a swimwear revolution was set to explode in the 1950s.
0:26:16 > 0:26:20We'd fallen in love with the flimsy, figure-hugging nylon costume
0:26:20 > 0:26:23like this.
0:26:23 > 0:26:29- Nylon was the wonder of the new age. - Beachwear has certainly changed
0:26:29 > 0:26:32since the days when Victorian maidens tiptoed gingerly
0:26:32 > 0:26:35down to the water's edge shrouded in thick wool.
0:26:37 > 0:26:40Scientists could engineer swimwear that could withstand
0:26:40 > 0:26:44the worst of the tide and still retain its shape.
0:26:44 > 0:26:48Man-made fibres seemed like a miracle fit for both sunbathing
0:26:48 > 0:26:51and swimming.
0:26:51 > 0:26:54I want to understand exactly what nylon is.
0:26:54 > 0:26:56How do you make a man-made fibre?
0:26:58 > 0:27:01Chemist David Smith from the University of York
0:27:01 > 0:27:05is going to show me how two unremarkable-looking chemicals
0:27:05 > 0:27:08revolutionised the swimming costume.
0:27:08 > 0:27:10Let's make nylon. What is it, first of all?
0:27:10 > 0:27:13So, nylon is a giant molecule, really long molecules.
0:27:13 > 0:27:15And what are these molecules made from?
0:27:15 > 0:27:18Well, they're made from two reagents that we have here,
0:27:18 > 0:27:21and they each have reactive groups, so they're going to react
0:27:21 > 0:27:24and form long chains, a bit like if I held hands with somebody else
0:27:24 > 0:27:27and somebody else and we built a long chain along the beach.
0:27:27 > 0:27:30We're going to pour the one reagent on top of the other
0:27:30 > 0:27:32and you've got to float it in down the side.
0:27:32 > 0:27:34Right, a bit like pouring cream on coffee.
0:27:34 > 0:27:36Exactly like that, yeah.
0:27:36 > 0:27:40In between the layers, you should see a film forming between the two.
0:27:40 > 0:27:41Yeah, yeah, I do, actually.
0:27:41 > 0:27:44So do I just penetrate the film, David?
0:27:44 > 0:27:48That's right, just to where the film is, and then agitate slightly,
0:27:48 > 0:27:50and you'll be able to then pull the film out.
0:27:50 > 0:27:51Oh, wow. Is that a bit of nylon?
0:27:51 > 0:27:53That's a bit of nylon that we've got there.
0:27:53 > 0:27:56So, what it shows, really, is that you can take two chemicals,
0:27:56 > 0:27:58mix them together and make a fabric.
0:27:58 > 0:28:01You don't have to wait for the sheep or for the cotton to grow.
0:28:01 > 0:28:02You can do it with chemicals.
0:28:02 > 0:28:05And is nylon itself waterproof?
0:28:05 > 0:28:08It dries very fast and the water doesn't penetrate very well,
0:28:08 > 0:28:10so certainly compared to what was around before nylon,
0:28:10 > 0:28:12it was a big step forward, especially for swimwear.
0:28:15 > 0:28:18By reinventing swimwear over the ages,
0:28:18 > 0:28:22we have coped with the changing tides of beach fashion.
0:28:22 > 0:28:27We wanted it all, a cossie for the sand and the surf.
0:28:27 > 0:28:32Nylon certainly made a splash on the beach, but what's it like wet?
0:28:32 > 0:28:35Looks like I can't escape one last dip.
0:28:46 > 0:28:50I'm off to buy a wetsuit.
0:28:57 > 0:29:02Timing the tide right for a dip makes life more convenient.
0:29:02 > 0:29:05But for commerce, it's vital.
0:29:08 > 0:29:12All around our coast, businesses run to the rhythm of the sea,
0:29:12 > 0:29:16especially the Port of Liverpool.
0:29:19 > 0:29:23The mouth of the Mersey yawns wide open into the Irish Sea.
0:29:23 > 0:29:30As the tide rushes in, the estuary swallows a vast deluge of water.
0:29:30 > 0:29:35The flood brings in seafood for the wildlife of the marshes.
0:29:35 > 0:29:42The tide also carries in cargo ships - big ones.
0:29:42 > 0:29:46They do a dangerous dance over sandbanks
0:29:46 > 0:29:48that can only be cleared at high water.
0:29:50 > 0:29:55It's a race against the tide twice a day.
0:30:00 > 0:30:05No wonder Liverpool has always kept a close eye on the tides.
0:30:05 > 0:30:09They've been measuring the rise and the fall of the sea here
0:30:09 > 0:30:14for over 250 years. It's the longest tidal record in the UK.
0:30:14 > 0:30:17Sailors watched the water so closely
0:30:17 > 0:30:22to try and work out what it's going to do next.
0:30:22 > 0:30:25Ray, as a Mersey skipper, do you carry tide tables on your boat?
0:30:25 > 0:30:27I do, yes, it's here right now, it's like a Bible.
0:30:27 > 0:30:30We have one of them all the time.
0:30:30 > 0:30:31- This is your Bible?- It certainly is.
0:30:31 > 0:30:33Time and tide wait for no man.
0:30:33 > 0:30:37But mariners did have to wait an awfully long time
0:30:37 > 0:30:40to get truly accurate tide tables.
0:30:45 > 0:30:47The riddle of the tides turns out to be
0:30:47 > 0:30:50much, much harder to crack than you'd think.
0:30:50 > 0:30:55There's more to predicting tides than the pull of the moon.
0:30:55 > 0:30:57You've got to add in the gravity of the sun,
0:30:57 > 0:31:00account for multiple elliptical orbits,
0:31:00 > 0:31:04the tilt of the earth. The complexity goes on.
0:31:04 > 0:31:07What about the depth of the sea, the shape of the coast?
0:31:07 > 0:31:12Over centuries, the best brains solved pieces of the puzzle,
0:31:12 > 0:31:15but before computers, tidal maths was too complex
0:31:15 > 0:31:17to be worked out in your head.
0:31:17 > 0:31:21So, calculating machines had to be invented.
0:31:21 > 0:31:26In the 1940s, all that effort to solve the riddle of the tides
0:31:26 > 0:31:30finally reached its high water mark here in Liverpool
0:31:30 > 0:31:33with the construction of a mechanical brain.
0:31:33 > 0:31:36The cogs and wheels of tide-predicting machines
0:31:36 > 0:31:41used to whirr away inside Bidston Observatory,
0:31:41 > 0:31:44on a hill overlooking the mighty Mersey.
0:31:45 > 0:31:49This site was once the nerve centre for global tide tables.
0:31:49 > 0:31:52Most of the British Empire ports
0:31:52 > 0:31:56relied on the calculations done at Bidston.
0:31:56 > 0:31:59But now the machines that crunched the numbers
0:31:59 > 0:32:02are a bit crunched themselves.
0:32:03 > 0:32:07Deep in storage at National Museums Liverpool,
0:32:07 > 0:32:11the tidal prediction machines are in bits.
0:32:13 > 0:32:17Now, for the first time in years, one of the mechanical brains
0:32:17 > 0:32:19is about to be re-assembled.
0:32:21 > 0:32:23Wow, look at that.
0:32:24 > 0:32:29Lots of brass, cast iron, steel axles,
0:32:29 > 0:32:32absolutely stunning, isn't it?
0:32:32 > 0:32:36- At the time, this was state of the art.- It was indeed, yes.
0:32:36 > 0:32:40When these wheels rotated, they could forecast the future,
0:32:40 > 0:32:43the future of the sea.
0:32:43 > 0:32:46But how?
0:32:46 > 0:32:51While the original machine is carefully pieced back together,
0:32:51 > 0:32:53I'm heading to the museum on Liverpool's quayside,
0:32:53 > 0:32:56where Alan Bowden has something to show me.
0:32:59 > 0:33:01So this is a model of a tide prediction machine.
0:33:01 > 0:33:04It's absolutely beautiful, but what are the main principles
0:33:04 > 0:33:08driving the computations, the predictions that it's making?
0:33:08 > 0:33:11It's actually quite a complex set of mathematical equations
0:33:11 > 0:33:14which depend on a number of variables,
0:33:14 > 0:33:16and on this little model we've only selected four variables.
0:33:16 > 0:33:20For instance, we've got the impact of the moon,
0:33:20 > 0:33:24which is the principal component on the earth's tides,
0:33:24 > 0:33:26we've got the impact of the sun,
0:33:26 > 0:33:29and then we have two other variables here, for instance,
0:33:29 > 0:33:32we have the eccentricity of the moon's orbit,
0:33:32 > 0:33:36and then on this one here we have the effect of the sun -
0:33:36 > 0:33:38it's higher in summer, lower in winter.
0:33:38 > 0:33:44Adjustments must also be made to take account of local variations
0:33:44 > 0:33:47like the shape of the coast.
0:33:47 > 0:33:51So this wire is the processor, this is the thing that amalgamates
0:33:51 > 0:33:55the readings from different variables and converts them to a line...
0:33:55 > 0:33:59And converts them to a line which gives us high tide
0:33:59 > 0:34:02and the low tide and the points in between.
0:34:02 > 0:34:07The full-scale machine had 42 variables
0:34:07 > 0:34:08and took one and a half days
0:34:08 > 0:34:13to run a year of tide predictions for one port.
0:34:13 > 0:34:17Liverpool became the world centre for tidal prediction
0:34:17 > 0:34:21thanks to one man - Arthur Doodson.
0:34:21 > 0:34:23He devoted his life to improving
0:34:23 > 0:34:27and perfecting tidal prediction machines at Bidston Observatory.
0:34:29 > 0:34:31But Arthur also needed workers to operate them -
0:34:31 > 0:34:34people he called computers.
0:34:35 > 0:34:37So you worked in the basement?
0:34:37 > 0:34:40We did. One of the machines was down here.
0:34:40 > 0:34:43Arthur Doodson's daughter-in-law
0:34:43 > 0:34:48worked on the wheels of tidal fortune here for 44 years.
0:34:48 > 0:34:52Valerie Doodson retired from Bidston, but now she's back.
0:34:53 > 0:34:58- Wow. Is this it?- This is where it all happened for the years
0:34:58 > 0:35:02that we operated the Doodson-Lege tide predicting machine.
0:35:02 > 0:35:06It was situated in this room facing this wall,
0:35:06 > 0:35:07but with a space behind it,
0:35:07 > 0:35:10cos we needed to get at the back to set it up.
0:35:10 > 0:35:13Well, that's an example of setting up the machine.
0:35:13 > 0:35:18One person set it up and another person checked the information.
0:35:18 > 0:35:20And who are these people?
0:35:20 > 0:35:22These are the tidal computers
0:35:22 > 0:35:28in the early part of the 1960s, and that's me, but don't tell anyone.
0:35:28 > 0:35:32Oh, wow! Wonderful.
0:35:32 > 0:35:37These girls probably are 16. 16 or 17.
0:35:37 > 0:35:40It has been said that he likes to surround himself
0:35:40 > 0:35:42with attractive young women.
0:35:42 > 0:35:45Well, I didn't like to say anything, but...
0:35:45 > 0:35:47So there we go.
0:35:47 > 0:35:50Very young to be doing such a difficult, responsible job.
0:35:50 > 0:35:52So what's this card here, Valerie?
0:35:52 > 0:35:55This is the setting card for Penang.
0:35:55 > 0:35:56But that's in Malaya?
0:35:56 > 0:36:01That's correct, yes. For 1965,
0:36:01 > 0:36:04and it's predicting the high and low water.
0:36:04 > 0:36:06The cards are very neatly filled in, aren't they?
0:36:06 > 0:36:07Very important.
0:36:07 > 0:36:11One test we had when we came for interview was a handwriting test.
0:36:11 > 0:36:13If your handwriting didn't meet the requirement,
0:36:13 > 0:36:14you didn't get the job.
0:36:14 > 0:36:18I have subsequently been called a perfectionist,
0:36:18 > 0:36:20because mistakes were not tolerated.
0:36:21 > 0:36:25During its heyday, Bidston prepared tide tables
0:36:25 > 0:36:28for ports across the British Empire.
0:36:28 > 0:36:31Their work was crucial during the Second World War.
0:36:33 > 0:36:36The Atlantic Wall has been penetrated.
0:36:36 > 0:36:40Indeed, the computers even predicted low tide for the D-Day landings,
0:36:40 > 0:36:46where avoiding submerged Nazi sea defences was vital to success.
0:36:46 > 0:36:49Now we have a solid foothold on Fortress Europa,
0:36:49 > 0:36:52men and materiel are poured onto the newly-won beachheads
0:36:52 > 0:36:53with every favourable tide.
0:36:55 > 0:36:59By the late 1960s, new electronic computers had taken over.
0:37:02 > 0:37:05The role of the mechanical machines and their operators
0:37:05 > 0:37:07has largely been forgotten.
0:37:08 > 0:37:11But now, after years of hibernation,
0:37:11 > 0:37:17the machine that predicted tides in the Second World War is reborn.
0:37:30 > 0:37:32This is absolutely wonderful.
0:37:32 > 0:37:36It's a little bit more exciting than looking at a modern circuit board.
0:37:40 > 0:37:43Looking back from an age in which calculations are conducted
0:37:43 > 0:37:46invisibly from within modern computer software,
0:37:46 > 0:37:50this incredible piece of mechanical hardware is a reminder
0:37:50 > 0:37:53that maths is beautiful, it's elegant,
0:37:53 > 0:37:55that it decodes universal mysteries.
0:37:55 > 0:37:59Without maths and without this very ingenious machine,
0:37:59 > 0:38:04we couldn't have solved the riddle of the tides.
0:38:11 > 0:38:16Ingenuity feeds the industry of Liverpool.
0:38:16 > 0:38:19The docks were built to trap precious seawater behind their gates,
0:38:19 > 0:38:23because at low tide, the water rushes away from the city.
0:38:25 > 0:38:29Nearby, that leaves Antony Gormley's Iron Men
0:38:29 > 0:38:33gazing wistfully after the retreating seas.
0:38:42 > 0:38:47Twice a day, the shallow sloping beaches of the north-west coast
0:38:47 > 0:38:49look more like a desert.
0:38:49 > 0:38:53When the sea shrinks away from Southport Pier,
0:38:53 > 0:38:56it becomes a walkway over the sand.
0:39:01 > 0:39:06Just a few miles further north at the resourceful resort of Blackpool,
0:39:06 > 0:39:08they've constructed their own ingenious contraption
0:39:08 > 0:39:13to harness the power of the town's big tides.
0:39:13 > 0:39:16DISCORDANT ORGAN NOTES
0:39:16 > 0:39:19The sweet music of the sea.
0:39:23 > 0:39:29It might not be very tuneful, but this is the tide talking
0:39:29 > 0:39:33through the pipes of a rather remarkable organ.
0:39:33 > 0:39:34My name's Liam Curtin,
0:39:34 > 0:39:39and with my friend John Gooding, we built the Blackpool High Tide Organ.
0:39:42 > 0:39:47Down on the beach, the tide is still out. It's on its way in.
0:39:47 > 0:39:51We can have a look at what powers the organ.
0:39:51 > 0:39:56So here is one of the ductile iron pipes attached to the sea wall.
0:39:56 > 0:40:02That feeds the organ at high tide, sea comes in, swells and falls,
0:40:02 > 0:40:06and as it swells, pushes air up there and into the organ.
0:40:06 > 0:40:10There's eight of these fanned out along the promenade.
0:40:11 > 0:40:15All organs need a source of air. In this case we're using the sea,
0:40:15 > 0:40:17but other organs might use bellows,
0:40:17 > 0:40:20something to push the air into the pipes,
0:40:20 > 0:40:24and to demonstrate this, we can go and look at a very famous organ.
0:40:32 > 0:40:36Well, here it is, the mighty Wurlitzer.
0:40:36 > 0:40:42HE PLAYS THE WURLITZER
0:40:48 > 0:40:52The bellows in this organ have replaced the sea in our organ,
0:40:52 > 0:40:56pushing air into the pipes in the same sort of way.
0:40:56 > 0:41:01That makes the bellows swell, so it makes it louder,
0:41:01 > 0:41:05and there's doors that can close to muffle pipes
0:41:05 > 0:41:08and a whole range of effects.
0:41:15 > 0:41:19You can play any tune on it, unlike the Blackpool High Tide Organ,
0:41:19 > 0:41:21which is more of an ambient thing,
0:41:21 > 0:41:25just responding to the chaos of the weather.
0:41:28 > 0:41:30The weather's got a bit worse,
0:41:30 > 0:41:33but in a way that's better for the organ,
0:41:33 > 0:41:37because there's a bit of swell and we can hear its chords now,
0:41:37 > 0:41:41and along with it we've got James Lancaster, a musician,
0:41:41 > 0:41:44who's come to play along with it.
0:41:44 > 0:41:50TRUMPET AND TIDAL ORGAN PLAY
0:42:12 > 0:42:14The tidal organ sits in screaming distance
0:42:14 > 0:42:17of Blackpool's more energetic attractions.
0:42:35 > 0:42:40The sea comes in and out, as the punters are shaken all about!
0:42:43 > 0:42:48The donkeys retreat as the water rises.
0:42:48 > 0:42:52For some, the daily ebb and flow up and down the beach
0:42:52 > 0:42:54is bad for business.
0:42:54 > 0:42:58But for others, it's a big draw.
0:42:58 > 0:43:05Further south, the power of the tide alone pulls people out to Jersey.
0:43:07 > 0:43:11The Channel Islands are one of our great natural wonders.
0:43:12 > 0:43:15Sitting on the edge of the Atlantic Ocean,
0:43:15 > 0:43:19they have an exceptionally high rise and fall of water.
0:43:21 > 0:43:24The heaving of the sea reveals secret caves...
0:43:25 > 0:43:28..before the tide closes them shut again.
0:43:31 > 0:43:35That ebb and flow makes this a magical, shape-shifting coast.
0:43:35 > 0:43:36At low water on Jersey,
0:43:36 > 0:43:42a submerged undersea world is exposed just offshore.
0:43:43 > 0:43:47Especially when there's a spring tide.
0:43:47 > 0:43:49That's when the moon and the sun line up.
0:43:49 > 0:43:55Their combined gravitational pull causes an extra-strong tidal effect.
0:44:01 > 0:44:06A natural performance Miranda can't resist.
0:44:08 > 0:44:12A spring tide is a fascinating time to explore the coast.
0:44:12 > 0:44:15Not only does the water come up really high,
0:44:15 > 0:44:18but more interestingly for me, it goes out really low,
0:44:18 > 0:44:22revealing wildlife that's usually hidden beneath the waves.
0:44:27 > 0:44:32The effect of the spring tide on Jersey is spectacular.
0:44:32 > 0:44:36So much of the seabed here lies just below water level
0:44:36 > 0:44:38that at low spring tide,
0:44:38 > 0:44:42parts of the island expand over two miles outwards.
0:44:42 > 0:44:46It leaves this old coastal fort high and dry,
0:44:46 > 0:44:48and this is where I'm heading.
0:44:48 > 0:44:51The Seymour Tower will be my base
0:44:51 > 0:44:54to explore an extraordinary landscape of temporary rock pools,
0:44:54 > 0:44:56teeming with wildlife.
0:44:58 > 0:45:03These miniature water worlds only exist for a few short hours.
0:45:03 > 0:45:07With the sea gone, I've got to get a move on.
0:45:07 > 0:45:11In no time this vast lunar landscape is going to be submerged again,
0:45:11 > 0:45:13and we've just got a very brief window
0:45:13 > 0:45:16to get out to the Seymour Tower and set up camp.
0:45:16 > 0:45:19And then tomorrow we can really explore the Atlantic
0:45:19 > 0:45:22surging in and out around us.
0:45:23 > 0:45:25- Hi!- Bob, how are you doing? - Very well!
0:45:25 > 0:45:27Bob Tompkins is my guide.
0:45:27 > 0:45:31He grew up on Jersey and knows every nook and cranny
0:45:31 > 0:45:33of this short-lived landscape.
0:45:37 > 0:45:39So what's the time window that we've got to get out there?
0:45:39 > 0:45:44Roughly three quarters of an hour to be on the safe side.
0:45:52 > 0:45:54I mean, the sands here are shifting all the time, all the time.
0:45:58 > 0:46:00The tide operates in a pincer movement here.
0:46:00 > 0:46:03It comes up through the gully on that side,
0:46:03 > 0:46:07but it's sweeping around the curve of the reef here
0:46:07 > 0:46:11and coming up through the beach this way as well.
0:46:11 > 0:46:14The sea can easily surround the unwary.
0:46:14 > 0:46:18Dashing for the slippery steps of this rescue tower
0:46:18 > 0:46:21to sit out the tide could save your life.
0:46:25 > 0:46:28Look at that! That is majestic, isn't it?
0:46:28 > 0:46:29Yeah.
0:46:30 > 0:46:32Can't believe we're finally here.
0:46:32 > 0:46:36- It seemed such a long way back there, and here we are.- Yeah.
0:46:38 > 0:46:40- My castle awaits.- Yep.
0:46:45 > 0:46:48Wow! Look at this. This is really special, isn't it?
0:46:48 > 0:46:52- Home from home. Get the fire going. - Wood-burning stove.- Yeah.
0:46:53 > 0:46:57From this Napoleonic fortress, I can explore the marine life
0:46:57 > 0:47:01the Atlantic is about to bring to my doorstep.
0:47:01 > 0:47:05The jeep beats a rapid retreat, but I'm staying.
0:47:05 > 0:47:08The ocean soon rushes in around me,
0:47:08 > 0:47:12transforming the tower into an island.
0:47:12 > 0:47:17Tomorrow, I'll explore the sea life stranded on the seabed around me,
0:47:17 > 0:47:20as the Atlantic rushes out again.
0:47:29 > 0:47:33The next morning it's me that's still stranded way offshore,
0:47:33 > 0:47:35waiting for the tide to turn.
0:47:35 > 0:47:39When it does, I'll be well-placed to scramble.
0:47:41 > 0:47:45I'm hoping as the water floods away
0:47:45 > 0:47:47that it's left some interesting wildlife
0:47:47 > 0:47:49trapped in the pools behind me.
0:47:53 > 0:47:56These mega rock pools won't be around for long.
0:47:56 > 0:47:58I have a 20-minute window to swim
0:47:58 > 0:48:01and see what the Atlantic has brought in.
0:48:04 > 0:48:06This has to be the weirdest thing I've ever done in a rock pool.
0:48:06 > 0:48:09I held out my hand and I felt something tickling on it,
0:48:09 > 0:48:11and it's actually a little brown shrimp,
0:48:11 > 0:48:14who normally hide away in little holes.
0:48:14 > 0:48:16They're actually coming up and sitting on my hand,
0:48:16 > 0:48:19and I think they're actually feeding off little bits of skin.
0:48:19 > 0:48:20This is very bizarre.
0:48:24 > 0:48:27It's amazing how quickly the water drains away.
0:48:27 > 0:48:30The rock pools shrink with every minute,
0:48:30 > 0:48:32leaving wildlife looking for cover.
0:48:35 > 0:48:38Well, surely the find of the day, this is a brown crab.
0:48:38 > 0:48:40A male brown crab.
0:48:40 > 0:48:43They don't find females around here for some reason.
0:48:43 > 0:48:46By the looks of things he's just shed his carapace.
0:48:46 > 0:48:48It's not quite hard, so he's probably come in here,
0:48:48 > 0:48:50where it's relatively protected.
0:48:50 > 0:48:55He can shed and have a few days to recover and harden up the next shell
0:48:55 > 0:48:58and then he'll be off out. Handsome chap.
0:49:07 > 0:49:10The water's rushing away from me fast,
0:49:10 > 0:49:16so now I can explore the very edge of the low spring tide on foot.
0:49:23 > 0:49:26The tide's gone out pretty far now,
0:49:26 > 0:49:28but it's left these little pools of water,
0:49:28 > 0:49:30and with rock pooling, every rock tells a story.
0:49:30 > 0:49:34You need to pick them all up and have a good look at them.
0:49:36 > 0:49:40This one looks good, I'll just turn that one over.
0:49:42 > 0:49:46You can see this beautiful snakelocks anemone there.
0:49:46 > 0:49:49You only ever find those actually in the water,
0:49:49 > 0:49:52they can't retract their tentacles like a beadlet anemone does.
0:49:52 > 0:49:54So those need to live in water.
0:49:54 > 0:49:57But this is interesting, there's this orange encrusting sponge,
0:49:57 > 0:50:00and you can see that it's formed a line there.
0:50:00 > 0:50:03That line will tell me where the low water mark is.
0:50:03 > 0:50:06That sponge needs to grow in water,
0:50:06 > 0:50:09and it won't grow any higher up that line.
0:50:09 > 0:50:12Let's put that back carefully, make sure everything's under water.
0:50:15 > 0:50:19Ordinarily, I'd have no place being here.
0:50:19 > 0:50:23I'm walking two miles offshore on what's normally the seabed.
0:50:23 > 0:50:26Here the sea life have to adopt strategies to survive.
0:50:27 > 0:50:31This cloud of green is actually thousands of tiny worms,
0:50:31 > 0:50:34known locally as mint sauce worms,
0:50:34 > 0:50:37who shrink into the sand at the sign of a predator.
0:50:39 > 0:50:42Over time, this spider crab shell has been camouflaged by seaweed,
0:50:42 > 0:50:47and banded dog whelks don't go anywhere without their armour.
0:50:48 > 0:50:52Creatures thrive in the rich soup of nutrients
0:50:52 > 0:50:55the tide conveniently washes their way twice a day.
0:50:57 > 0:51:00Farmers also make the most of the Atlantic's bounty
0:51:00 > 0:51:02to fatten up millions of rock oysters.
0:51:07 > 0:51:10Out on the edge is a really special place to be.
0:51:10 > 0:51:14Much of this environment is under water for most of the time,
0:51:14 > 0:51:17and it's only at these really, really low spring tides
0:51:17 > 0:51:18that you can get out here.
0:51:18 > 0:51:20So much more than just rocks and seaweed.
0:51:20 > 0:51:22This place is teeming with life.
0:51:28 > 0:51:32But with the spring tide now on the turn,
0:51:32 > 0:51:36I have a bit of a trek to make it all the way back to dry land.
0:51:43 > 0:51:46Where the sea has room to breathe,
0:51:46 > 0:51:49the water can disappear well offshore.
0:51:49 > 0:51:53But where the tide is trapped, beware.
0:51:54 > 0:51:59The Isle of Anglesey sits snugly next to mainland Wales.
0:51:59 > 0:52:02Between them lies the Menai Strait,
0:52:02 > 0:52:06a straitjacket for the surging tide.
0:52:06 > 0:52:08With nowhere else to go,
0:52:08 > 0:52:11the water must speed up to make it through the rocky channel.
0:52:13 > 0:52:17Fast-flowing water floods the strait with food
0:52:17 > 0:52:22that makes this the ideal location for fattening up mussels.
0:52:22 > 0:52:27Sea farmers collect their mussels in specially designed boats,
0:52:27 > 0:52:32which do a merry dance to harvest their crop.
0:52:34 > 0:52:36Whatever their craft,
0:52:36 > 0:52:41all around the Anglesey coast, sailors respect the raging tide.
0:52:41 > 0:52:44Even the bigger boats seek shelter.
0:52:44 > 0:52:47They hide behind sturdy sea walls.
0:52:49 > 0:52:51But I'm not hiding.
0:52:51 > 0:52:56For me, the final riddle of the tides is how to tame them.
0:52:57 > 0:53:02I'm about to take on the great surge of the Atlantic tide
0:53:02 > 0:53:07as it squeezes around the ferocious rocks and reefs just off Anglesey.
0:53:07 > 0:53:10And I'm going to be in a boat not much bigger than a matchstick.
0:53:12 > 0:53:18Nigel Dennis was one of the first men to kayak right around Britain.
0:53:18 > 0:53:22He knows the waters here are amongst the most challenging we have.
0:53:22 > 0:53:26The tide creates powerful surges in the sea.
0:53:26 > 0:53:30The water races on, carrying kayaks with it for fun.
0:53:30 > 0:53:35These tidal races are a test of both skill and stomach.
0:53:35 > 0:53:38Now it's my turn.
0:53:38 > 0:53:40I'm a beginner, Nigel.
0:53:40 > 0:53:44OK, this already looks moderately serious to me.
0:53:44 > 0:53:47You're going to be stretched a little bit today.
0:53:47 > 0:53:49So how much paddling have we done?
0:53:49 > 0:53:52Well, I've done quite a lot of what I call canoeing
0:53:52 > 0:53:55- on inland waters and rivers. - Kayaking, kayaking, this is.
0:53:55 > 0:53:57This is something very different, isn't it?
0:53:57 > 0:53:59This is kayaking, this is for the ocean.
0:53:59 > 0:54:02And have you done anything in tides, moving water?
0:54:02 > 0:54:04I've done a little bit, Nigel, a little bit.
0:54:04 > 0:54:07But I can tell this is way beyond anything I've experienced before.
0:54:07 > 0:54:12Right, OK. So the tide's going to be pushing us towards the rocks,
0:54:12 > 0:54:17towards the race, and we're going to drop down through the water.
0:54:17 > 0:54:21And what's the chance of me turning a kayak upside-down and capsizing?
0:54:21 > 0:54:23Today, 50/50.
0:54:23 > 0:54:26- That's pretty high odds! - The first bit is easy.
0:54:26 > 0:54:29- I'll have to do some practicing! - The first bit is easy!
0:54:29 > 0:54:32- Yes, yes!- OK, I'll give you a hand with your boat.- OK.
0:54:42 > 0:54:46So, Nigel, in this little moment of calm, well, it's not really calm,
0:54:46 > 0:54:48all these things are relative for me,
0:54:48 > 0:54:54but can you just tell me what tides mean to a kayaker, a sea kayaker?
0:54:55 > 0:55:02Well, it's really important that kayakers understand what it means.
0:55:02 > 0:55:06You can go around the corner on a calm day and end up in a tide race,
0:55:06 > 0:55:09and people won't have the skill, or the power,
0:55:09 > 0:55:12to get out of the flowing water,
0:55:12 > 0:55:15so they'll actually be sucked straight through the race.
0:55:15 > 0:55:20So you need skills, power, but also a deep knowledge of how tides work?
0:55:20 > 0:55:22I mean, we call it seamanship, really.
0:55:22 > 0:55:25Some people have a natural understanding
0:55:25 > 0:55:28and other people never learn.
0:55:28 > 0:55:29THEY LAUGH
0:55:31 > 0:55:36And just when I'm thinking I've got the hang of it,
0:55:36 > 0:55:38the tide trips me up.
0:55:49 > 0:55:54OK. Just give us your boat, just hop back in...
0:55:56 > 0:55:58Just plonk yourself back in.
0:56:00 > 0:56:01Good! Well done.
0:56:03 > 0:56:06How did you did get to the flat water and then capsize?
0:56:06 > 0:56:08HE LAUGHS
0:56:08 > 0:56:10Lack of concentration.
0:56:12 > 0:56:15The rocky outcrops don't just produce swirling waters.
0:56:15 > 0:56:20They also create a curious feeling of claustrophobia,
0:56:20 > 0:56:23which adds to my anxiety.
0:56:24 > 0:56:27Caught between two emotions, fear and exhilaration.
0:56:28 > 0:56:33Are we going into the tide or with it, are we going with the tide?
0:56:33 > 0:56:36Yes, the first tiny bit of tide, you can just see it up ahead.
0:56:36 > 0:56:40You call it a tiny bit of tide but I can see white horses...
0:56:40 > 0:56:43The first heart in mouth moment.
0:56:43 > 0:56:48A tide race off one of the most dangerous coasts in Britain.
0:57:01 > 0:57:04It's kind of exciting. A real thrill.
0:57:04 > 0:57:07But I'm sweating buckets trying not to turn upside down.
0:57:07 > 0:57:13These waves are so big that in the troughs I can see nothing but sea.
0:57:23 > 0:57:27We're working with the tide, not fighting against it,
0:57:27 > 0:57:31and I can really feel its full force pushing me onwards.
0:57:36 > 0:57:39Just keep paddling, you're doing really well.
0:57:39 > 0:57:43Nice and relaxed, that's good!
0:57:43 > 0:57:47My battle against the tide was a one-off.
0:57:47 > 0:57:50I'm just happy to have made it through in one piece.
0:57:50 > 0:57:54But all around our coast, every minute of every day,
0:57:54 > 0:57:57the tides rule the rhythm of people's lives.
0:57:59 > 0:58:03I've just discovered how tricky tides can be.
0:58:03 > 0:58:07After capsizing and an awful lot of paddling,
0:58:07 > 0:58:12I'm back on the beach taking in one of nature's great free shows,
0:58:12 > 0:58:16the ebb and flow of this vast body of water,
0:58:16 > 0:58:22whose restless motion is driven by the heavens.
0:58:22 > 0:58:24It's awe-inspiring.
0:58:52 > 0:58:55Subtitles by Red Bee Media Ltd