0:00:05 > 0:00:07The waters around the UK
0:00:07 > 0:00:11hide treasures and surprises we rarely get to see.
0:00:13 > 0:00:16Powered by Arctic currents to the north
0:00:16 > 0:00:18and the Gulf Stream from the south,
0:00:18 > 0:00:21our island occupies a unique position
0:00:21 > 0:00:22in the Atlantic ocean.
0:00:25 > 0:00:27'I'm explorer Paul Rose.
0:00:27 > 0:00:31'I was Base Commander of the British Antarctic survey for ten years
0:00:31 > 0:00:35'and I've scuba-dived all around the world.'
0:00:35 > 0:00:39I've got to be careful doing this! Oop!
0:00:41 > 0:00:43But now I've come home
0:00:43 > 0:00:45to lead a team of specialists
0:00:45 > 0:00:48to uncover the secrets beneath our seas.
0:00:50 > 0:00:51Divers up!
0:00:51 > 0:00:55Joining me is marine biologist Tooni Mahto.
0:00:55 > 0:00:57Her underwater expertise
0:00:57 > 0:00:59will reveal the unexpected riches
0:00:59 > 0:01:01of British marine life.
0:01:01 > 0:01:05This is a colony of loads of individual animals.
0:01:05 > 0:01:08Journalist and underwater archaeologist Frank Pope
0:01:08 > 0:01:13will examine the bigger picture of our relationship with the sea
0:01:13 > 0:01:15and explore our maritime history.
0:01:15 > 0:01:20The remains of the 60-odd crew men are still inside.
0:01:25 > 0:01:30This series will take us on a journey right around the British coastline,
0:01:30 > 0:01:34to uncover the most startling underwater wonders.
0:01:35 > 0:01:40This time, we're exploring Britain's south coast.
0:01:40 > 0:01:41It's our busiest coastline,
0:01:41 > 0:01:43packed with ferries,
0:01:43 > 0:01:45fun-seekers and pleasure boats.
0:01:45 > 0:01:46But below it all,
0:01:46 > 0:01:50there are mysterious wrecks and magical creatures.
0:01:50 > 0:01:54This time we're investigating our bustling southern shores.
0:01:54 > 0:01:59Beneath our waves is a world of secrets.
0:02:13 > 0:02:17Our expedition begins in Poole,
0:02:17 > 0:02:19bang in the middle of Britain's south coast.
0:02:22 > 0:02:23This busy seaport
0:02:23 > 0:02:26has been a hub of maritime activity
0:02:26 > 0:02:28since the 12th century.
0:02:28 > 0:02:31But just metres below the waves lies a secret,
0:02:31 > 0:02:35which has lain untouched for centuries.
0:02:35 > 0:02:39Out there in the Swash Channel, archaeologists have uncovered a mysterious wooden shipwreck.
0:02:42 > 0:02:45It's a spectacular wreck, we know that much, but not much more.
0:02:45 > 0:02:48- It's full of secrets and mystery. - Look at that!
0:02:48 > 0:02:51- Have you ever seen anything like that?- Certainly not.
0:02:51 > 0:02:54That's a very intricate carving.
0:02:54 > 0:02:57No-one knows when it sailed, no-one knows exactly who built it,
0:02:57 > 0:02:59where it was going, or even how it sank.
0:02:59 > 0:03:02- There's no records of this thing at all. - I'm really looking forward to this.
0:03:02 > 0:03:05I've used all kinds of tools underwater,
0:03:05 > 0:03:08but not on something as delicate and as precise and as important
0:03:08 > 0:03:10as maritime archaeology.
0:03:10 > 0:03:12So I'm super-keen on this one.
0:03:12 > 0:03:15- You will be careful won't you, Paul? - Yes, I'll do me best!
0:03:19 > 0:03:22Frank and I are joining a team of archaeologists from Bournemouth University
0:03:22 > 0:03:26who have been working on the site night and day.
0:03:32 > 0:03:37We want to find out all we can about this puzzling wreck.
0:03:39 > 0:03:44'I didn't realise how close we would be to passing ships.'
0:03:44 > 0:03:47Here comes the Cherbourg ferry
0:03:47 > 0:03:50in the main shipping lane called the Swash Channel.
0:03:50 > 0:03:52It's defined by... You can see these buoys -
0:03:52 > 0:03:55there's the green one there and the red one right there.
0:03:55 > 0:03:57And our wreck, the Swash Channel wreck,
0:03:57 > 0:04:00is right underneath us, on the very edge of the channel.
0:04:01 > 0:04:04The wreck would have laid there undiscovered,
0:04:04 > 0:04:06seven metres below the surface,
0:04:06 > 0:04:08were it not for a dredging boat
0:04:08 > 0:04:10clearing a channel for the ferries.
0:04:10 > 0:04:12'Head archaeologist Dave Parham
0:04:12 > 0:04:15'has drawn a sketch map of the site.'
0:04:15 > 0:04:18And this was actually part of the bow castle.
0:04:18 > 0:04:20We've also got the gudgeons for the rudder.
0:04:20 > 0:04:23- But the rudder is in front of... - The rudder has come off,
0:04:23 > 0:04:27it's become displaced and swept underneath the wreck and then covered in sediment.
0:04:27 > 0:04:32- If it hadn't been covered in sediment it wouldn't have survived. - So lucky!- Unusual to find a rudder.
0:04:33 > 0:04:39'The archaeologists believe the wreck dates from the 17th century.
0:04:39 > 0:04:41'With no historical records,
0:04:41 > 0:04:44'her true identity remains unknown.'
0:04:47 > 0:04:51As an archaeologist, your job is to try and put together the different clues
0:04:51 > 0:04:55that might give you a picture of what the wreck was
0:04:55 > 0:04:57and the sort of people that lived in her.
0:04:57 > 0:04:59The thing is, when you first get down to it,
0:04:59 > 0:05:01it's going to be enormously confusing,
0:05:01 > 0:05:04its going to be a very distorted picture, and often incomplete.
0:05:04 > 0:05:07What you're going to do, boys,
0:05:07 > 0:05:09is go down to this part of the wreck here.
0:05:09 > 0:05:13What we want you to do is dig along here to try and define this edge.
0:05:13 > 0:05:16Be aware there are fairly delicate things lying around.
0:05:16 > 0:05:20If you're going to sit down, look at what you're sitting on first.
0:05:20 > 0:05:22LAUGHTER
0:05:22 > 0:05:23Are we ready to go?
0:05:23 > 0:05:25Have a good one.
0:05:33 > 0:05:36'Lying at only seven metres,
0:05:36 > 0:05:39'it takes just moments to reach the wreck.'
0:05:43 > 0:05:45Oh, look at this!
0:05:45 > 0:05:47Oh, wow.
0:05:47 > 0:05:51Look at that!
0:05:58 > 0:06:00Now, this is interesting.
0:06:00 > 0:06:05- These large pieces of wood look like ribs of some kind, don't they?- Yep.
0:06:05 > 0:06:10It's beautiful condition, you see here where the wood has been freshly exposed.
0:06:10 > 0:06:13It's absolutely beautiful, it's mint condition.
0:06:13 > 0:06:14That's fabulous.
0:06:15 > 0:06:17'As an archaeologist himself,
0:06:17 > 0:06:21'Frank starts to recognise parts of the ship we're swimming over.'
0:06:21 > 0:06:24You can see the big frames of the ship.
0:06:24 > 0:06:26Gosh, she was really quite a heavy ship.
0:06:26 > 0:06:30And these amorphous lumps...
0:06:30 > 0:06:32These are actually the heads of iron bolts
0:06:32 > 0:06:34that would have helped held the ship together.
0:06:34 > 0:06:38They've kind of erupted in this reaction with the seawater.
0:06:42 > 0:06:44'While Frank looks for more clues,
0:06:44 > 0:06:49'I join one of the team excavating new parts of the wreck.'
0:06:49 > 0:06:50This here's the dredge
0:06:50 > 0:06:55and it's like an industrial underwater vacuum cleaner.
0:06:55 > 0:06:59You know, I've used these water dredges
0:06:59 > 0:07:01as part of salvage work before,
0:07:01 > 0:07:05but I must say I've never used them to try and reveal an ancient ship.
0:07:07 > 0:07:12You can see I can quite carefully expose these ancient timbers,
0:07:12 > 0:07:15just a centimetre at a time.
0:07:16 > 0:07:18The sediment, sucked up here,
0:07:18 > 0:07:21gets pumped out again fifteen metres away,
0:07:21 > 0:07:24so it doesn't settle back over the wreck.
0:07:27 > 0:07:30Blimey, I nearly sucked a fish up then! Look at that.
0:07:30 > 0:07:32He must be a strong swimmer.
0:07:35 > 0:07:39'Every tree has a unique pattern of growth rings,
0:07:39 > 0:07:43'which can be matched against a global database to identify it.
0:07:43 > 0:07:45'By analysing the timbers,
0:07:45 > 0:07:47'the archaeologists have discovered
0:07:47 > 0:07:51'that the ship was built from wood felled in 1629.
0:07:51 > 0:07:54'They can even tell that this wood
0:07:54 > 0:07:57'came from close to the border between Germany and Holland.'
0:08:01 > 0:08:03When you see what I'm doing here
0:08:03 > 0:08:07and then look at the amount of wood that's been exposed,
0:08:07 > 0:08:11you get a pretty good idea of how hard work it is. This is a big job.
0:08:13 > 0:08:15'From her size and design,
0:08:15 > 0:08:19'the archaeologists know this was a merchant vessel,
0:08:19 > 0:08:22'and the discovery of a layer of pine over the hull
0:08:22 > 0:08:26'gives them a clue as to where she was headed.'
0:08:26 > 0:08:31This is beautiful. So what you can really see here is the two types of wood.
0:08:31 > 0:08:34This is the actual hull of the ship here.
0:08:34 > 0:08:39This is the hard wood and then the sacrificial layer on top which is made of pine.
0:08:39 > 0:08:42'This protective cladding
0:08:42 > 0:08:47'was only found on ships heading for the warm waters of the tropics.'
0:08:47 > 0:08:48It's fascinating to see.
0:08:48 > 0:08:50I've never seen this on a site before
0:08:50 > 0:08:54and you can only see it on a couple of other sites around the world.
0:08:54 > 0:08:58'This ship was part of the very beginnings of trade with the East,
0:08:58 > 0:09:01'but it was carrying more than just cargo.'
0:09:01 > 0:09:02Oh, holy smokes!
0:09:02 > 0:09:04I've just figured out what this is.
0:09:04 > 0:09:06This is a cannon.
0:09:06 > 0:09:10I could have just swum over this and think it was a white rock.
0:09:10 > 0:09:14'This is just one of six cannon the team have discovered,
0:09:14 > 0:09:18'making her a heavily-armed merchant ship.'
0:09:18 > 0:09:19This is a big old gun,
0:09:19 > 0:09:22probably a 24-pounder.
0:09:23 > 0:09:27'The excavation work has revealed much about this important ship,
0:09:27 > 0:09:31'but Dave Parham has taken Frank to see one discovery
0:09:31 > 0:09:34'which marks this wreck as something quite extraordinary -
0:09:34 > 0:09:36'the ship's rudder.'
0:09:36 > 0:09:40Up here, we have the carving of a human head.
0:09:40 > 0:09:43Wow! Look at that.
0:09:43 > 0:09:45You've got the hair, his face,
0:09:45 > 0:09:48an eye socket with an eye in it,
0:09:48 > 0:09:54his nose and a moustache on his mouth.
0:09:54 > 0:09:59I have never seen anything like it.
0:09:59 > 0:10:03It's absolutely beautiful.
0:10:03 > 0:10:05Wow, what a thing!
0:10:05 > 0:10:08This is like finding a pharaoh's tomb.
0:10:08 > 0:10:12'This intricate carving is one of three they've found so far.
0:10:12 > 0:10:16'It covers just the top part of the rudder,
0:10:16 > 0:10:19'which is over eight-metres long and weighs almost two tonnes.'
0:10:19 > 0:10:23This isn't just any old wreck, this was a really high-profile ship
0:10:23 > 0:10:25and you can tell that by the carving.
0:10:30 > 0:10:32'Piecing together the clues,
0:10:32 > 0:10:35'we can now start to build a picture
0:10:35 > 0:10:37'of what this ship may have looked like.
0:10:38 > 0:10:41'This was a large wooden trading ship,
0:10:41 > 0:10:45'built at a time when Charles I was on our throne
0:10:45 > 0:10:50'and Europe was engaged in the very beginnings of empire building.
0:10:50 > 0:10:52'From the timber,
0:10:52 > 0:10:54'we know she sailed from Holland or Germany
0:10:54 > 0:10:57'and was headed to the tropics.
0:10:57 > 0:11:00'But the heavy cannon and ornate carvings
0:11:00 > 0:11:04'suggest this was far more than just a standard merchant ship.
0:11:11 > 0:11:15A beautiful wreck, my God.
0:11:15 > 0:11:18You know what's so poignant is
0:11:18 > 0:11:22you've got this wonderfully-carved wood that's just been exposed
0:11:22 > 0:11:27and you can almost see the chisel marks of the guys who made this. This was hundreds of years ago -
0:11:27 > 0:11:29probably 1630 that this stuff was made -
0:11:29 > 0:11:33and it's right there. And by touching it, you really feel
0:11:33 > 0:11:37like you're connecting with the guys who built that and who sailed in it.
0:11:38 > 0:11:40'After months of excavation,
0:11:40 > 0:11:42'the fate of this important wreck
0:11:42 > 0:11:45'now hangs in the balance.
0:11:45 > 0:11:46'Saving a ship like this
0:11:46 > 0:11:51'is a complex and expensive process.
0:11:51 > 0:11:53'But the archaeologists are running out of time,
0:11:53 > 0:11:56'as the wreck is being destroyed before their eyes.
0:11:56 > 0:11:59'Later on, we'll be back to find out why.'
0:12:03 > 0:12:07The English Channel is the world's busiest shipping lane,
0:12:07 > 0:12:11so it's no surprise that our southern waters are full of wrecks.
0:12:12 > 0:12:16But the shipwrecks of the Channel don't just give us a glimpse back in time...
0:12:18 > 0:12:22they're also home to some surprising sea creatures.
0:12:23 > 0:12:27There's one animal which is renowned for hiding out in wrecks.
0:12:27 > 0:12:30Rumoured to be big, vicious,
0:12:30 > 0:12:32and no friend to divers.
0:12:36 > 0:12:38The beast in question is the conger eel
0:12:38 > 0:12:41and despite being one of the most common animals in our waters,
0:12:41 > 0:12:43it's also one of the most secretive.
0:12:43 > 0:12:45We really don't know much about them.
0:12:45 > 0:12:48I want to find out if this giant beast
0:12:48 > 0:12:50really does deserve its fearsome reputation.
0:12:52 > 0:12:54'Here in Plymouth,
0:12:54 > 0:12:57'I've found some conger experts.
0:12:57 > 0:13:01'But they're not biologists, they're expert anglers.'
0:13:01 > 0:13:04So what is it about the conger eel
0:13:04 > 0:13:06that evokes such a passion for it?
0:13:06 > 0:13:07I'll tell you what it is.
0:13:07 > 0:13:10It's mean, moody
0:13:10 > 0:13:13and magnificent.
0:13:13 > 0:13:16And I think that sums up the conger eel.
0:13:17 > 0:13:20'Bryn Lavis and Mike Millman
0:13:20 > 0:13:22'run the British Conger Club
0:13:22 > 0:13:25'and are devoted to all things conger.'
0:13:26 > 0:13:30Now then, what's the biggest one that's ever been caught in British waters?
0:13:30 > 0:13:34133-and-a-quarter pounds, by Vic Evans out of Brixham.
0:13:34 > 0:13:36I mean, it's a mighty eel.
0:13:36 > 0:13:38- Boy, that is a whopper.- Yeah.
0:13:38 > 0:13:41133 pounds and the width of this one?
0:13:41 > 0:13:45It's about 42 inches at its widest point.
0:13:45 > 0:13:4842 inches - hang on... Bigger than my chest, and how long?
0:13:48 > 0:13:51Nine feet...plus.
0:13:51 > 0:13:54- Nine feet, two inches, I think it was.- Holy smokes!
0:13:54 > 0:13:56So when you catch them
0:13:56 > 0:13:59and all of a sudden you've got this huge great thing on board,
0:13:59 > 0:14:00what happens then?
0:14:00 > 0:14:03- Well, it's not finished. - No, I can imagine!
0:14:03 > 0:14:06Cos there must be teeth going and there's a lot of activity.
0:14:06 > 0:14:09It's not so much the teeth that are the problem,
0:14:09 > 0:14:12they've got very small teeth.
0:14:12 > 0:14:14But they've got a terrific clamp pressure.
0:14:14 > 0:14:16Think of a crocodile, an alligator.
0:14:16 > 0:14:19If they've got hold of something and try to get away,
0:14:19 > 0:14:21- they start revolving... - So here's your finger?
0:14:21 > 0:14:25- Oh gone, just twisted off. - It is ripping off?
0:14:25 > 0:14:28Yes, it's rip. It's not a bite off, it's rip off.
0:14:28 > 0:14:30Ow!
0:14:31 > 0:14:33'The Conger Club are sport fishermen
0:14:33 > 0:14:37'and they throw the congers back in once they've landed them,
0:14:37 > 0:14:39'but I don't want to catch one.
0:14:39 > 0:14:42'I want to dive into conger territory
0:14:42 > 0:14:45'to see just how close I can get
0:14:45 > 0:14:48'to one of these ferocious beasts.
0:14:48 > 0:14:51'Although congers are found all along our southwest coast,
0:14:51 > 0:14:56'the deep waters of Plymouth Harbour are famous for congers.
0:14:56 > 0:15:00'Massive eels have been caught just metres from these shores.'
0:15:09 > 0:15:13Conger eels are really opportunistic hunters - they'll eat anything, even each other!
0:15:13 > 0:15:16I'm going to take some mackerel with me to entice them out of their lair.
0:15:16 > 0:15:19And I'm going to take no chances whatsoever,
0:15:19 > 0:15:22so I've got these special Kevlar gloves just in case.
0:15:27 > 0:15:29Away you go, Paul.
0:15:35 > 0:15:36'Can you hear me?'
0:15:36 > 0:15:39Yeah, I can hear you loud and clear.
0:15:39 > 0:15:41Have a good dive, fellas.
0:15:41 > 0:15:42Good luck with the congers.
0:15:46 > 0:15:48'30 metres down is a wreck,
0:15:48 > 0:15:52'one of almost 5,000 in the English Channel.
0:15:55 > 0:15:57'It should be the perfect conger hideout.'
0:16:07 > 0:16:09There's a fair bit of nice life down here.
0:16:09 > 0:16:11That's a good sign, look at that.
0:16:13 > 0:16:17'It won't be easy to get close to a conger.
0:16:18 > 0:16:20'They're ambush predators
0:16:20 > 0:16:23'and tend to hide away in nooks and crannies
0:16:23 > 0:16:25'so they can lash out at passing prey.
0:16:26 > 0:16:29'That's not the kind of close encounter I'm after!'
0:16:31 > 0:16:35It stands to reason we should find them in some of these holes.
0:16:58 > 0:17:00Oh, there she is!
0:17:03 > 0:17:04Look at this.
0:17:07 > 0:17:10Now, with any luck,
0:17:10 > 0:17:12with some of this squid bait,
0:17:12 > 0:17:14I just might get her out.
0:17:17 > 0:17:19I've got to be careful doing this
0:17:19 > 0:17:22because she's got very sharp teeth.
0:17:27 > 0:17:30Come on then, girl, out you come.
0:17:37 > 0:17:39Ooh!
0:17:39 > 0:17:41Ha!
0:17:45 > 0:17:49You notice I'm saying "her" and not "it" or "him",
0:17:49 > 0:17:54and that's because I'm absolutely certain that she is a female.
0:17:54 > 0:17:59Cos we never see males in our waters. Never, not one.
0:17:59 > 0:18:03'Female congers spend up to 15 years in our waters
0:18:03 > 0:18:07'before heading to deep Atlantic seas to breed.
0:18:07 > 0:18:11'Scientists think they may be drawn to our rich waters
0:18:11 > 0:18:13'so they can fatten up before spawning.
0:18:13 > 0:18:17'But they've still no idea where the males go.'
0:18:19 > 0:18:20Here she comes.
0:18:22 > 0:18:24Here she comes.
0:18:25 > 0:18:27'She seems pretty fearless.
0:18:27 > 0:18:30'I'm amazed how close she's letting me get to her.'
0:18:32 > 0:18:33Ooh!
0:18:33 > 0:18:34Ha-ha!
0:18:37 > 0:18:40I don't think we're going to get this one out, you know.
0:18:40 > 0:18:42She's too smart for me,
0:18:42 > 0:18:46no surprise there.
0:18:46 > 0:18:47See you.
0:18:51 > 0:18:54'That conger was less than a metre long,
0:18:54 > 0:18:59'certainly not one of the giants the anglers were talking about.
0:18:59 > 0:19:01'So I'm going to keep on looking.'
0:19:12 > 0:19:15These are the boilers.
0:19:15 > 0:19:19And you can imagine all these great holes are perfect places for conger.
0:19:25 > 0:19:27I've found one!
0:19:27 > 0:19:29She's just a beauty!
0:19:38 > 0:19:40She is a beauty.
0:19:43 > 0:19:44Look at her!
0:19:48 > 0:19:50I don't even have to feed this one,
0:19:50 > 0:19:53she's just curious as to what's going on.
0:20:20 > 0:20:24I know the anglers said they were mean, moody and magnificent,
0:20:24 > 0:20:27At the moment, I'm just going to stick with the last one -
0:20:27 > 0:20:30magnificent. She is beautiful.
0:20:44 > 0:20:47Hello! How are you?
0:20:47 > 0:20:49HE LAUGHS
0:20:51 > 0:20:53Hello!
0:20:56 > 0:20:59Well, this is a tremendous experience.
0:20:59 > 0:21:02I'm not going to stick my fingers in there so she can get it,
0:21:02 > 0:21:03that's for sure.
0:21:05 > 0:21:09'She's certainly not the fearsome monster I was led to expect.
0:21:09 > 0:21:11'In its own environment,
0:21:11 > 0:21:15'the beautiful conger eel is a secretive and magnificent creature.'
0:21:18 > 0:21:20'And in all my years of diving,
0:21:20 > 0:21:24'I can honestly say I've never been kissed by a fish before!'
0:21:24 > 0:21:28I think that was the perfect conger eel encounter.
0:21:28 > 0:21:31I don't think you could possibly get any better.
0:21:31 > 0:21:35You could get a sense of the beauty and grace of this fabulous animal,
0:21:35 > 0:21:38even though she was one side of the boiler and I was on the other.
0:21:38 > 0:21:40I'm in love!
0:21:48 > 0:21:51The calm seas and warm climate of the south
0:21:51 > 0:21:55bring a huge variety of marine animals to these shores.
0:21:55 > 0:21:57But they're not the only ones who flock here.
0:22:00 > 0:22:03The wildlife has to share these seas.
0:22:06 > 0:22:10In Dorset's Studland Bay, there's a conflict of interest
0:22:10 > 0:22:15between our actions and the needs of some very special marine creatures.
0:22:15 > 0:22:19Tooni went to investigate.
0:22:19 > 0:22:22This bay is home to one of Britain's most unexpected inhabitants.
0:22:22 > 0:22:24Small in size, but large in character,
0:22:24 > 0:22:28you might think you'd only see them in tropical waters.
0:22:28 > 0:22:31But Studland Bay is famous for its seahorses.
0:22:33 > 0:22:37Six years ago, local conservationist Steve Trewhella
0:22:37 > 0:22:39discovered a pregnant seahorse here,
0:22:39 > 0:22:43suggesting that Studland Bay is home to a breeding colony.
0:22:43 > 0:22:46I know it sounds silly, but when we're looking for seahorses
0:22:46 > 0:22:48you have to go into seahorse mode.
0:22:48 > 0:22:52You have to think like a seahorse. Where would you be if you were a seahorse?
0:22:52 > 0:22:55They are very, very hard to find.
0:22:58 > 0:23:02Studland Bay is now recognised as one of the most important seahorse sites in Europe,
0:23:02 > 0:23:05and there's a good reason they're here.
0:23:07 > 0:23:11'Just a few metres deep, lies this bed of thick eel grass,
0:23:11 > 0:23:13'a perfect seahorse habitat,
0:23:13 > 0:23:16'but one that makes them difficult to find.'
0:23:18 > 0:23:23So, Steve, what's the best method to try to find seahorses in the eel grass?
0:23:23 > 0:23:27A combination of extreme patience and good eyesight!
0:23:27 > 0:23:29You have to just really take your time
0:23:29 > 0:23:32- and just sort of sweep through carefully.- OK.
0:23:34 > 0:23:37Eel grass needs shallow, protected waters to flourish,
0:23:37 > 0:23:41so the sheltered bays of the south coast are ideal.
0:23:41 > 0:23:48Eel grass beds are incredibly important for a whole range of species,
0:23:48 > 0:23:54because it provides this fantastic wealth of places to hide,
0:23:54 > 0:23:56it would be incredibly difficult
0:23:56 > 0:23:58for a predator to come in here and find anything,
0:23:58 > 0:24:02as it's proving for us to find a seahorse.
0:24:13 > 0:24:16Ha-ha!
0:24:16 > 0:24:20Look! I have found a spiny seahorse.
0:24:24 > 0:24:27I know you're not meant to get sentimental about creatures,
0:24:27 > 0:24:31but she's so beautiful.
0:24:31 > 0:24:32Astonishing!
0:24:33 > 0:24:35'Seahorses may not look like it,
0:24:35 > 0:24:37'but they are in fact fish.
0:24:37 > 0:24:39'They blend into the weeds,
0:24:39 > 0:24:41'and prey upon passing tiny animals.'
0:24:43 > 0:24:46And these little spines that are coming off her head,
0:24:46 > 0:24:49they help her camouflage herself
0:24:49 > 0:24:51to basically disappear into the eel grass.
0:25:10 > 0:25:14'We've only just discovered that seahorses are breeding here,
0:25:14 > 0:25:16'and yet we could be about to lose them.
0:25:16 > 0:25:21'The rich eel grass essential for their survival is incredibly fragile
0:25:21 > 0:25:25'and is being destroyed...by us.'
0:25:28 > 0:25:30'While I'm with the seahorses,
0:25:30 > 0:25:34'Frank is finding out how this precious habitat is being damaged.'
0:25:39 > 0:25:42These mooring buoys look pretty harmless,
0:25:42 > 0:25:44but underneath this float and the rope
0:25:44 > 0:25:48there's about a ten-metre length of chain sitting on the sea bed.
0:25:48 > 0:25:51And every time the tide changes,
0:25:51 > 0:25:55that chain scythes round in a circle and before long,
0:25:55 > 0:25:58you've got a 20-metre wide bald patch on the sea bed.
0:26:01 > 0:26:04These chains are the big problem.
0:26:04 > 0:26:08Just adjacent to it, it's just bare sand
0:26:08 > 0:26:13and I literally can't see any eel grass growing around me.
0:26:13 > 0:26:18I mean, it's cleared as far as I can see.
0:26:31 > 0:26:33And it's not just the buoys.
0:26:33 > 0:26:34At the height of the summer,
0:26:34 > 0:26:38there are up to 300 boats dropping anchor in this bay.
0:26:41 > 0:26:47It's difficult to persuade people that doing something like chucking an anchor into what looks like weeds,
0:26:47 > 0:26:51is actually destroying a very vulnerable and critical habitat.
0:26:54 > 0:26:57'To study the impact on the seahorse population,
0:26:57 > 0:27:00'Steve has been closely monitoring them.
0:27:01 > 0:27:05'He has a special licence to tag these tiny creatures
0:27:05 > 0:27:07'and track their movements.'
0:27:08 > 0:27:12Bearing in mind they're not radio tags, they're purely visual -
0:27:12 > 0:27:14you have re-find the animal -
0:27:14 > 0:27:16it proves that they're highly territorial.
0:27:16 > 0:27:19We're going back to the same location every week
0:27:19 > 0:27:23and re-finding many of these tagged seahorses.
0:27:23 > 0:27:26Well, I sincerely hope that you see her again later in the year
0:27:26 > 0:27:28and that you manage to see her a few times.
0:27:28 > 0:27:30Well, hopefully we will,
0:27:30 > 0:27:32and next time we see her she may well be with a mate,
0:27:32 > 0:27:36so, hopefully breeding successfully - that's what she's come here to do.
0:27:39 > 0:27:41Bye-bye, beautiful.
0:27:54 > 0:27:57When you look out on Studland Bay,
0:27:57 > 0:28:01it's easy to see how the destruction of this precious seahorse habitat
0:28:01 > 0:28:02is going unnoticed.
0:28:04 > 0:28:07By highlighting the plight of the seahorses
0:28:07 > 0:28:10and the importance of the eel grass they live in,
0:28:10 > 0:28:14perhaps the conservationists can now raise public awareness
0:28:14 > 0:28:17and keep these magical creatures safe.
0:28:23 > 0:28:27'Just north of Studland Bay, Frank and I are back with the team
0:28:27 > 0:28:30'investigating the Swash Channel wreck,
0:28:30 > 0:28:33'one of the archaeological finds of the century.
0:28:33 > 0:28:35'But time is running out...'
0:28:41 > 0:28:44The archaeologists are working every hour they can
0:28:44 > 0:28:47to document and excavate the mysterious Swash Channel wreck.
0:28:47 > 0:28:50Frank is underwater with them now
0:28:50 > 0:28:54to investigate why the archaeologists have to work so fast
0:28:54 > 0:28:55in order to save this wreck.
0:28:56 > 0:28:59All of what you see here is only here
0:28:59 > 0:29:01because it was once covered by sediment.
0:29:01 > 0:29:03That sediment's now gone.
0:29:03 > 0:29:06'The natural erosion of the sea bed,
0:29:06 > 0:29:08'which has exposed the wreck from beneath the sand
0:29:08 > 0:29:11'has also exposed her to danger.'
0:29:11 > 0:29:16First of all, you get the scouring from the sand as the currents swish past
0:29:16 > 0:29:18and then you also expose it to oxygen
0:29:18 > 0:29:21and therefore bacterial decay starts eating the wood.
0:29:21 > 0:29:25But there is one further, much more sinister threat
0:29:25 > 0:29:27that this wreck faces.
0:29:27 > 0:29:31'She's now under attack from some small but brutal sea creatures.'
0:29:38 > 0:29:42At Bournemouth University, marine archaeologist Paola Palma
0:29:42 > 0:29:46is trying to find out how fast the ship is being destroyed.
0:29:46 > 0:29:49The surface of the wreck is being eaten away
0:29:49 > 0:29:53by a small crustacean called a gribble.
0:29:53 > 0:29:55- Hi.- Hi.
0:29:55 > 0:29:56'Tooni's gone to her lab
0:29:56 > 0:30:00'to see these shipwreck wreckers for herself.'
0:30:00 > 0:30:03So these are obviously very tiny
0:30:03 > 0:30:07and they don't go inside the core of the wood,
0:30:07 > 0:30:09but they stay on the surface.
0:30:09 > 0:30:13And what they do, they cause all this superficial degradation.
0:30:13 > 0:30:16- Bits flaking...- Yes, bits falling off everywhere.- Absolutely.
0:30:16 > 0:30:20The damage that these organisms cause is fast
0:30:20 > 0:30:23and is quite ferocious.
0:30:23 > 0:30:26But as damaging as the gribble is,
0:30:26 > 0:30:30there's an even more destructive animal at large on the wreck.
0:30:30 > 0:30:34So the gribbles are causing this roughing of the surface,
0:30:34 > 0:30:38but it's something different that's causing this actual real structural damage.
0:30:38 > 0:30:40It is indeed. This is the shipworm.
0:30:40 > 0:30:43And you can see it even better here.
0:30:43 > 0:30:46You see a perfect example
0:30:46 > 0:30:50of the kind of tunnels that are left by the shipworm.
0:30:50 > 0:30:52You can also smell it, probably!
0:30:52 > 0:30:54- I can! - It smells quite badly, doesn't it?
0:30:54 > 0:30:56And it's something that...
0:30:56 > 0:31:00looks like this...
0:31:01 > 0:31:06It turns out shipworm is not a worm at all, but a mollusc,
0:31:06 > 0:31:08like a mussel or a cockle.
0:31:08 > 0:31:09They burrow into the wood,
0:31:09 > 0:31:13leaving behind them these chalk-lined tunnels.
0:31:15 > 0:31:17But to see the full extent of the damage,
0:31:17 > 0:31:21we need to take a look inside.
0:31:21 > 0:31:24A bit of archaeological baking.
0:31:24 > 0:31:25Back in a minute.
0:31:29 > 0:31:32As you can see, they are quite impressive.
0:31:32 > 0:31:35You can even see, very clearly,
0:31:35 > 0:31:38the shell of the organism.
0:31:38 > 0:31:43I guess the main thing about the shipworm is that it's not actually biting into the wood,
0:31:43 > 0:31:48it's literally boring into the wood with these incredibly impressive bivalve shells.
0:31:48 > 0:31:52And it's only when you see them on the close-up on the microscope,
0:31:52 > 0:31:55that you see every single serrated edge.
0:31:55 > 0:31:58And it's actually this rotation of this shell
0:31:58 > 0:32:01that's literally diving and digging down
0:32:01 > 0:32:02into the timbers of the shipwreck.
0:32:04 > 0:32:07Parts of this wreck could be entirely destroyed by these creatures
0:32:07 > 0:32:11in just a few short years.
0:32:11 > 0:32:12It's an absolute disaster.
0:32:12 > 0:32:15We're not just talking about one single organism,
0:32:15 > 0:32:18but we're talking about millions of organisms.
0:32:18 > 0:32:23So the damage that they cause is absolutely, you know, horrendous.
0:32:23 > 0:32:26We're seeing that already, in one year,
0:32:26 > 0:32:28the damage is irreversible.
0:32:32 > 0:32:34'Back on the Swash Channel wreck,
0:32:34 > 0:32:37'lead archaeologist Dave Parham
0:32:37 > 0:32:41'is all too aware of the damage these creatures cause.'
0:32:41 > 0:32:45This is what the timber surface would've been like when it was first uncovered.
0:32:45 > 0:32:50Outside of that you can see shipworm and gribble tunnels.
0:32:50 > 0:32:54This is really a case study in how well sediment can preserve wood.
0:32:54 > 0:32:57Cos when this is covered, this is protected.
0:32:57 > 0:33:00But give it a few years and it'll be gone completely.
0:33:02 > 0:33:07And that same degradation you can see all the way along the line.
0:33:07 > 0:33:10This wood is rotting away before our eyes.
0:33:10 > 0:33:12So there's a real sense of urgency here.
0:33:14 > 0:33:18With the site under attack and the clock ticking,
0:33:18 > 0:33:20Dave and his team must do everything they can
0:33:20 > 0:33:23to preserve this precious ship.
0:33:23 > 0:33:26Frank and I will be looking into this later.
0:33:29 > 0:33:34Our southern shores host some of Britain's favourite holiday destinations,
0:33:34 > 0:33:38with seaside attractions and beaches drawing millions of people.
0:33:38 > 0:33:42But sometimes the real treasures are just beneath our feet.
0:33:42 > 0:33:45Tooni's gone to Brighton to see what's beside us,
0:33:45 > 0:33:47when we're beside the sea.
0:33:51 > 0:33:53Brighton, in East Sussex,
0:33:53 > 0:33:55was one of the UK's first seaside resorts
0:33:55 > 0:33:58and still throngs with visitors today,
0:33:58 > 0:34:01attracting over eight million people a year.
0:34:01 > 0:34:06And many of them will visit Brighton's famous palace pier.
0:34:10 > 0:34:12It was built in 1899,
0:34:12 > 0:34:15at a time when the well-to-do liked to stride out into the ocean,
0:34:15 > 0:34:19gaze across the sea, decide which small nation to conquer next,
0:34:19 > 0:34:21all without getting their feet wet.
0:34:28 > 0:34:31But I'm not here for the fairground rides and candy floss,
0:34:31 > 0:34:35I've come to see the attractions below the pier.
0:34:35 > 0:34:38It may have been built for pleasure,
0:34:38 > 0:34:41but this pier has created a huge artificial reef.
0:34:43 > 0:34:46And we've been given special permission to go underneath it.
0:34:50 > 0:34:53This 500-metre long intricate lattice of steel beams
0:34:53 > 0:34:58creates the habitat that allows marine life to flourish.
0:34:58 > 0:35:01That looks good. Does it feel OK?
0:35:01 > 0:35:03- MUFFLED - That feels good.
0:35:21 > 0:35:25It's very eerie being down here underneath the pier.
0:35:25 > 0:35:29Funny to think of everybody playing the slot machines and eating doughnuts above.
0:35:32 > 0:35:34'The first arrivals to colonise this space
0:35:34 > 0:35:36'would have been the "clingers"
0:35:36 > 0:35:38'- barnacles and mussels.
0:35:38 > 0:35:40'Without rocks to latch on to,
0:35:40 > 0:35:42'these creatures would not be here.
0:35:42 > 0:35:44'But the steel beams of the pier
0:35:44 > 0:35:49'effectively create a 12-metre skyscraper for them to live on.'
0:35:49 > 0:35:53This is just absolutely jam-packed full of mussels,
0:35:53 > 0:35:56all filter feeding and open.
0:35:56 > 0:35:59And where one thing comes, many others will too
0:35:59 > 0:36:02and you get an entire eco-system,
0:36:02 > 0:36:04so predator and prey.
0:36:04 > 0:36:06But it's the mussels and the starfish
0:36:06 > 0:36:09that are right at the basis of that food chain here.
0:36:12 > 0:36:15These starfish are the mussels' worst enemy.
0:36:15 > 0:36:17They're actually voracious predators,
0:36:17 > 0:36:20but they feed on mussels in quite an interesting way.
0:36:20 > 0:36:23The starfish yank the shell apart
0:36:23 > 0:36:25and then evert their stomachs.
0:36:25 > 0:36:30So they literally pull their stomach out through their mouth,
0:36:30 > 0:36:32sink it into the mussel
0:36:32 > 0:36:35and digest the mussel in its own shell.
0:36:39 > 0:36:43Everywhere you look, it's just mussel, after mussel, after mussel,
0:36:43 > 0:36:47being eaten by starfish, after starfish, after starfish.
0:36:52 > 0:36:55'And mussels aren't their only prey.
0:36:55 > 0:37:01'This whelk will soon succumb to the starfish's deadly embrace.'
0:37:07 > 0:37:09Look at this amazing fish.
0:37:09 > 0:37:11It's a gurnard.
0:37:11 > 0:37:14They live completely on the sea floor, don't really swim that much.
0:37:14 > 0:37:19Camouflage is their main defence against predators.
0:37:23 > 0:37:25What we're swimming over at the moment
0:37:25 > 0:37:29is pretty much what the sea floor would have been like
0:37:29 > 0:37:32had the Victorians not built this pier above.
0:37:32 > 0:37:36Flat, barren with not much for life to cling on to.
0:37:38 > 0:37:40Here, on the other hand,
0:37:40 > 0:37:45marine life has completely encrusted the surfaces of these metal structures.
0:37:49 > 0:37:50SHE LAUGHS
0:37:50 > 0:37:53Little tompot blenny
0:37:53 > 0:37:57just hiding in this pipe here.
0:37:57 > 0:37:59They're really beautiful fish.
0:37:59 > 0:38:03Just goes to show that every single nook and cranny
0:38:03 > 0:38:06is utilised by one animal or another.
0:38:09 > 0:38:12'It may have started as a Victorian playground,
0:38:12 > 0:38:15'but this pier is now a thriving eco-system,
0:38:15 > 0:38:18'home to millions of sea creatures.'
0:38:18 > 0:38:21- SHE LAUGHS - Now you see him, now you don't!
0:38:24 > 0:38:25It's remarkable.
0:38:25 > 0:38:30'It's good to know that sometimes our actions help marine life to prosper...
0:38:30 > 0:38:33'even if it's entirely accidental.'
0:38:42 > 0:38:44Good down there?
0:38:44 > 0:38:48Yep, it's very, very murky.
0:38:48 > 0:38:51It's crazy and gloomy down there.
0:38:51 > 0:38:53And it's hilarious just coming out
0:38:53 > 0:38:56and watching people walking along on the pier above you
0:38:56 > 0:38:58and hearing this thumping music,
0:38:58 > 0:39:01when you've just been down amongst the peace and quiet
0:39:01 > 0:39:03and the gloom of the mussel beds.
0:39:03 > 0:39:05Fantastic.
0:39:14 > 0:39:19Nearly 200 kilometres away from the bustle of Brighton is Lyme Bay,
0:39:19 > 0:39:22part of Dorset's sweeping Jurassic coast.
0:39:22 > 0:39:27This huge sheltered cove, warmed by the gulf stream,
0:39:27 > 0:39:30is one of the country's richest areas of marine life
0:39:30 > 0:39:33and home to beautiful British corals.
0:39:33 > 0:39:36But it's also an area vital to our fishing industry.
0:39:38 > 0:39:40Scallops are one of my favourite foods
0:39:40 > 0:39:45and the ones here in Lyme Bay are just legendary.
0:39:45 > 0:39:47But while we might all enjoy a tasty fish supper,
0:39:47 > 0:39:51how much do we really know about the journey our seafood takes
0:39:51 > 0:39:55from the sea floor to our dinner plate?
0:39:56 > 0:40:00Increasing numbers of us choose to buy free-range chickens
0:40:00 > 0:40:02or organic beef.
0:40:02 > 0:40:05But how many of us ask how our seafood is sourced?
0:40:07 > 0:40:09Most scallops are caught by dredging.
0:40:09 > 0:40:14Dredgers are great heavy metal rakes that get dragged along the sea bed,
0:40:14 > 0:40:16a bit like my fingers in the sand.
0:40:16 > 0:40:18And they're very, very efficient,
0:40:18 > 0:40:21collecting thousands upon thousands of scallops.
0:40:21 > 0:40:24But the problem is they collect everything on the sea floor,
0:40:24 > 0:40:27not just the scallops.
0:40:28 > 0:40:33'To see first-hand the impact dredging may have on our seabed,
0:40:33 > 0:40:36'Tooni has gone out into Lyme Bay.'
0:40:36 > 0:40:40There's a lot of debate about the pros and cons of dredging.
0:40:40 > 0:40:43Is our love of seafood putting the marine environment at risk,
0:40:43 > 0:40:46or can we find a way for the two to peacefully co-exist?
0:40:48 > 0:40:50'I'm going in,
0:40:50 > 0:40:54'to explore the scallop beds which get regularly dredged.'
0:40:56 > 0:41:00'The only scallops left here are the ones too small for the dredge nets.'
0:41:09 > 0:41:11SHE GIGGLES
0:41:16 > 0:41:18Such funny animals!
0:41:19 > 0:41:23They are total comedy molluscs.
0:41:23 > 0:41:25Love them.
0:41:25 > 0:41:28It's as though they're puppets being pulled by strings.
0:41:28 > 0:41:30Off you go.
0:41:30 > 0:41:33SHE LAUGHS
0:41:34 > 0:41:37That movement is actually the adductor muscle inside them
0:41:37 > 0:41:41which opens and shuts the shell.
0:41:41 > 0:41:45But unfortunately, it's that that we're so keen on eating.
0:41:45 > 0:41:48'Although the dredgers are designed
0:41:48 > 0:41:50'to leave the smaller scallops behind,
0:41:50 > 0:41:53'as they trawl a path across the sea bed
0:41:53 > 0:41:55'there's little else left in their wake.'
0:41:56 > 0:42:03Eugh. Such a muddy, horrible bit of seabed.
0:42:04 > 0:42:06It just feels really desolate,
0:42:06 > 0:42:09like a desert, essentially.
0:42:09 > 0:42:14I don't know. It really does feel like some huge destructive force
0:42:14 > 0:42:16has really gone through the whole place
0:42:16 > 0:42:20and just left it a real wasteland.
0:42:24 > 0:42:25'But left alone,
0:42:25 > 0:42:29'the sea bed can look very different.
0:42:29 > 0:42:32'I've come to another part of the bay
0:42:32 > 0:42:35'where the sea floor is scattered with large boulders.
0:42:35 > 0:42:37'These can damage the towing gear,
0:42:37 > 0:42:39'so this area has never been dredged.'
0:42:43 > 0:42:47'This reef is home to some extraordinary creatures.
0:42:47 > 0:42:53'These pink sea fans are actually slow-growing, cold-water corals.'
0:43:03 > 0:43:06This is a colony of loads of individual animals,
0:43:06 > 0:43:11growing in this wonderful fan-shaped structure.
0:43:11 > 0:43:14Now, they're all aligned, perpendicular to the current,
0:43:14 > 0:43:16which flows directly through them.
0:43:16 > 0:43:20That's so they get the maximum amount of food.
0:43:23 > 0:43:25Now the thing about pink sea fans is
0:43:25 > 0:43:28they're exceptionally slow-growing.
0:43:28 > 0:43:33This colony here would be about 10 to 15 years old.
0:43:35 > 0:43:37What a beautiful perch of reef.
0:43:39 > 0:43:43Not something you'd expect off the south coast of Britain.
0:43:46 > 0:43:49To protect this fragile marine environment,
0:43:49 > 0:43:54the government has now made part of Lyme Bay an exclusion zone.
0:43:54 > 0:43:57Within these 155 square kilometres,
0:43:57 > 0:44:00no scallop dredging is allowed.
0:44:02 > 0:44:05But not everyone is a fan of the protection scheme.
0:44:05 > 0:44:10The fishermen here feel that the exclusion zone is too big
0:44:10 > 0:44:13and that they are paying the price.
0:44:14 > 0:44:18Nick Prust has been fishing this area since he was 15.
0:44:18 > 0:44:22A lot of our most lucrative grounds are now taken.
0:44:22 > 0:44:26What we're saying is, within the Lyme Bay closure area,
0:44:26 > 0:44:28there are areas that are not reef,
0:44:28 > 0:44:30that hold considerable stocks of scallops
0:44:30 > 0:44:33- that could still be fished.- Right.
0:44:33 > 0:44:35The worrying part is the speed that it's all happening.
0:44:35 > 0:44:39To us, it's too much, too quick.
0:44:39 > 0:44:41What do you think are the solutions for Lyme Bay?
0:44:41 > 0:44:44Areas should be opened up, away from the reefs,
0:44:44 > 0:44:45we know where they are,
0:44:45 > 0:44:48and let the fishing industry continue to fish,
0:44:48 > 0:44:51because it'll work.
0:44:56 > 0:44:57This is a complex issue
0:44:57 > 0:45:02and tensions are understandably high.
0:45:02 > 0:45:06Is there a way to protect the livelihoods of our fishermen,
0:45:06 > 0:45:10without destroying our slow-growing corals?
0:45:16 > 0:45:18We're a nation of fish-eaters
0:45:18 > 0:45:21and it's our demand that drives the dredging industry,
0:45:21 > 0:45:24so it doesn't help to point the finger at fishermen
0:45:24 > 0:45:26whose livelihood depends on that dredging.
0:45:28 > 0:45:33There are no easy answers, but ultimately we all have a choice.
0:45:33 > 0:45:35So the next time you buy fish,
0:45:35 > 0:45:39it's worth asking where it comes from and how it's been caught.
0:45:45 > 0:45:49'Delicate corals aren't the only secrets hidden in Lyme Bay.'
0:45:49 > 0:45:52Its strategic position and calm waters
0:45:52 > 0:45:55led to it becoming the site of a key naval base
0:45:55 > 0:45:59which played a crucial role in both world wars.
0:46:01 > 0:46:04'Frank is delving into the fascinating story
0:46:04 > 0:46:07'of a truly incredible naval invention.'
0:46:09 > 0:46:12She was a British submarine called the M2
0:46:12 > 0:46:16and she's got a unique place in Royal Naval history.
0:46:16 > 0:46:21The HMS M2 was built in 1920
0:46:21 > 0:46:25and was originally fitted with a single 12-inch gun.
0:46:27 > 0:46:29But after four years,
0:46:29 > 0:46:31she was withdrawn from service
0:46:31 > 0:46:35and reassigned for experimental use.
0:46:35 > 0:46:37The navy had a cunning idea.
0:46:37 > 0:46:39They took the huge gun off the M2
0:46:39 > 0:46:42and replaced it with a watertight aircraft hangar.
0:46:42 > 0:46:46Then they commissioned a miniature two-seat biplane
0:46:46 > 0:46:47that fitted inside it,
0:46:47 > 0:46:50and could be catapulted off the front.
0:46:50 > 0:46:54Suddenly, the navy had an incredible new weapon.
0:46:54 > 0:46:57They had the range and stealth of a submarine,
0:46:57 > 0:47:00but they also had an eye in the sky.
0:47:02 > 0:47:06The ingenious plan was to send her ahead of the battle fleet
0:47:06 > 0:47:07as a reconnaissance scout.
0:47:07 > 0:47:10The sub would surface,
0:47:10 > 0:47:13its tiny plane unfolded and launched,
0:47:13 > 0:47:15all within a matter of minutes.
0:47:21 > 0:47:22'As a marine archaeologist,
0:47:22 > 0:47:26'I've always been fascinated by the history of the M2
0:47:26 > 0:47:29'and the dive support team are keen to hear her story.'
0:47:29 > 0:47:32That's obviously them launching the plane out the hangar,
0:47:32 > 0:47:35but look at how low in the water she is.
0:47:35 > 0:47:38- That looks hairy to me. - No freeboard there at all.
0:47:38 > 0:47:40The pilot would sit there with the engine going...
0:47:40 > 0:47:41HE IMITATES ENGINE
0:47:41 > 0:47:44..screaming, and then go...
0:47:44 > 0:47:45and give the thumbs up,
0:47:45 > 0:47:48and then on the deck beside him is the stoker.
0:47:48 > 0:47:51The stoker is the guy that can launch the catapult,
0:47:51 > 0:47:53but he can't actually do it himself,
0:47:53 > 0:47:56because you have to wait for the captain's word.
0:47:56 > 0:47:58So he signals up to the seaman on the conning tower,
0:47:58 > 0:48:01who turns to the captain and goes, "Ready to launch, Sir?"
0:48:01 > 0:48:06Meanwhile the guy is still... And then the captain goes, "Launch",
0:48:06 > 0:48:09and the seaman goes "OK, launch" and goes like this to the stoker
0:48:09 > 0:48:12who finally goes "Boof", and releases the catapult
0:48:12 > 0:48:17and they hit 60 knots in - how far is that? About 40 foot.
0:48:20 > 0:48:22It was an ambitious design.
0:48:22 > 0:48:24But perhaps it's no surprise
0:48:24 > 0:48:28that this eccentric vessel wasn't without its problems.
0:48:30 > 0:48:34On the 26th January 1932 during routine exercises,
0:48:34 > 0:48:36the M2 disappeared.
0:48:38 > 0:48:41Eight days later, she was found at the bottom of the ocean.
0:48:42 > 0:48:45One of the main things that they had to do in training,
0:48:45 > 0:48:49was to cut the amount of time that it would take them to get to the surface,
0:48:49 > 0:48:52and get that plane off, so they could hide that submarine again.
0:48:55 > 0:48:58'All attempts to lift the submarine failed,
0:48:58 > 0:49:02'so no-one's absolutely sure why the M2 sank.
0:49:02 > 0:49:06'She's still lying 30 metres below the surface,
0:49:06 > 0:49:08'just as she was almost 80 years ago.'
0:49:16 > 0:49:20'As we descend the line, it soon becomes obvious we've got a problem.'
0:49:25 > 0:49:28'We've dived into a thick bloom of plankton.'
0:49:32 > 0:49:34So where is the ship?
0:49:44 > 0:49:46Here we are and we've made the M2,
0:49:46 > 0:49:49but, my God, we could be anywhere.
0:49:49 > 0:49:52But anyway, there in the murk you can see...
0:49:54 > 0:49:55Oh, I've lost it.
0:49:59 > 0:50:02Frank to surface, Frank to surface.
0:50:02 > 0:50:05We cannot see a thing down here.
0:50:05 > 0:50:08I'm afraid we're going to have to call this off. Over.
0:50:08 > 0:50:12'OK. Got that, loud and clear. Thank you.'
0:50:12 > 0:50:16'It's a huge disappointment,
0:50:16 > 0:50:20'but the M2 has intrigued me for too long to give up now.
0:50:20 > 0:50:23'I'll be back when the water has cleared.'
0:50:32 > 0:50:36We were here three weeks ago and the visibility was just terrible.
0:50:36 > 0:50:39We could hardly see our hands in front of our faces.
0:50:39 > 0:50:42But the word is that the plankton bloom has died off
0:50:42 > 0:50:44and the visibility has cleared right up.
0:50:44 > 0:50:47Hopefully this time we can see something and have a look around.
0:50:57 > 0:51:02OK, I've got a lot more vis now.
0:51:04 > 0:51:08Wow, here she is, looming out of the murk.
0:51:11 > 0:51:14Absolutely wonderful.
0:51:19 > 0:51:22The scale of the thing takes your breath away.
0:51:22 > 0:51:24Magnificent.
0:51:34 > 0:51:39So, this here is the periscope.
0:51:45 > 0:51:47And here is the conning tower
0:51:47 > 0:51:52where the officers would have stood when the submarine was at the surface
0:51:52 > 0:51:54and they'd be scanning the sea.
0:51:58 > 0:52:00And then when the time came,
0:52:00 > 0:52:05they would give the order to launch the airplane up in the sky.
0:52:09 > 0:52:12'The amazing thing about the wreck of the M2
0:52:12 > 0:52:15'is that 80 years after she sank,
0:52:15 > 0:52:18'she's almost completely intact.
0:52:18 > 0:52:22'Which means the clues as to why she sank are still here.'
0:52:25 > 0:52:28Here is the aircraft hangar.
0:52:28 > 0:52:34This is where the miniature biplane was stored.
0:52:37 > 0:52:39Look at this, it's incredible.
0:52:42 > 0:52:46You can see that these doors are still wide open,
0:52:46 > 0:52:52this is the prime suspect here for what caused the end of the M2.
0:52:58 > 0:53:03These crews were trying very, very hard to make this concept work.
0:53:03 > 0:53:06The question is, were they trying too hard?
0:53:08 > 0:53:11Perhaps this was opened too fast
0:53:11 > 0:53:13when the submarine came to the surface.
0:53:13 > 0:53:15As the aircraft was being pushed out,
0:53:15 > 0:53:17the sea rushed in,
0:53:17 > 0:53:20flooded the interior of the submarine
0:53:20 > 0:53:23and sent it down to the bottom where we see it today.
0:53:26 > 0:53:31'Many believe the sinking of the M2 was down to human error,
0:53:31 > 0:53:35'but it could have been a technical malfunction.
0:53:35 > 0:53:37'She sank so fast
0:53:37 > 0:53:40'that no-one lived to tell the tale.'
0:53:43 > 0:53:46During the attempts to salvage the M2,
0:53:46 > 0:53:49all of the access hatches were sealed with concrete.
0:53:49 > 0:53:53They only ever recovered two bodies.
0:53:53 > 0:54:00So the remains of the 60-odd crew men are still inside.
0:54:00 > 0:54:04The M2 is a designated military grave,
0:54:04 > 0:54:07it's a steel coffin on the sea bed.
0:54:11 > 0:54:14'This unique wreck is a poignant reminder
0:54:14 > 0:54:17'of what an unforgiving place the ocean can be.'
0:54:23 > 0:54:26Back outside Poole harbour,
0:54:26 > 0:54:29the archaeologists excavating the mysterious Swash Channel wreck
0:54:29 > 0:54:33are fighting to save her.
0:54:33 > 0:54:36They may not know her full story,
0:54:36 > 0:54:40but they do know what an important discovery they have on their hands.
0:54:44 > 0:54:48It's interesting and important because we've got bits of ship that don't exist anywhere else.
0:54:48 > 0:54:50If you were to summarise what you've learnt so far?
0:54:50 > 0:54:53We've learnt, since the beginning of this really...
0:54:53 > 0:54:56Initially this was quite a small wreck of unknown character,
0:54:56 > 0:55:00now we know it's a large wreck, it's high-status, it's in these carvings.
0:55:00 > 0:55:03It's built and constructed to trade out to the tropics
0:55:03 > 0:55:06in a period when this was something new.
0:55:06 > 0:55:10What this ship was engaged in, and other ships like it were engaged in,
0:55:10 > 0:55:14is the reason why we have Japanese cars and Chinese videos.
0:55:14 > 0:55:18So actually, in world-history terms, this is an important object.
0:55:18 > 0:55:21But you are now engaged in this race,
0:55:21 > 0:55:24because this thing is deteriorating fast, right?
0:55:24 > 0:55:26So you're in a big, big race.
0:55:26 > 0:55:29We've watched it fall apart in front of our eyes for five years.
0:55:29 > 0:55:32But you can only do one thing at a time.
0:55:32 > 0:55:35'With such rapid deterioration,
0:55:35 > 0:55:38'there's pressure on the team to preserve the ship.
0:55:40 > 0:55:44'And the basics of preservation are a lot simpler than you might think.
0:55:44 > 0:55:47'Some of the wreck can be covered up
0:55:47 > 0:55:49'and protected for the future.'
0:55:49 > 0:55:55What happens is all the sediment finds its way into the nooks and the crannies between these sandbags
0:55:55 > 0:55:57and that actually forms a seal.
0:55:57 > 0:56:00It might sound a bit rudimentary, but it actually really works.
0:56:00 > 0:56:05'And what can't be covered, can at least be recorded.'
0:56:05 > 0:56:11What you can do is take pictures of exactly what the sea bed looks like
0:56:11 > 0:56:14and build that up into a sort of photomosaic.
0:56:14 > 0:56:18And I do row after row after row,
0:56:18 > 0:56:21so that all is not lost -
0:56:21 > 0:56:23when this wreck is physically gone,
0:56:23 > 0:56:25the information isn't.
0:56:31 > 0:56:34'Ultimately, the best way to preserve a shipwreck
0:56:34 > 0:56:36'is to lift it from the water altogether.
0:56:36 > 0:56:39'But the expense and logistics involved
0:56:39 > 0:56:41'make that almost impossible.'
0:56:43 > 0:56:47'But remarkably, that's just what's going to happen
0:56:47 > 0:56:50'to large parts of the Swash Channel wreck.'
0:56:51 > 0:56:54We're going to raise the first 12 metres of the bow,
0:56:54 > 0:56:57the rest of it, we're going to bury in situ and leave it there.
0:56:57 > 0:57:00But to you archaeologists, it seems quite routine.
0:57:00 > 0:57:05Let's chop it right off and bring it up. In archaeological terms, that's probably quite normal.
0:57:05 > 0:57:06No, it's not normal at all!
0:57:06 > 0:57:10- It's completely extraordinary, no-one's done it for 30 years.- Wow!
0:57:10 > 0:57:12Last time in Britain it was in the Mary Rose.
0:57:12 > 0:57:15It's as extraordinary as I thought then!
0:57:17 > 0:57:21Raising the Swash Channel wreck will be an arduous task
0:57:21 > 0:57:24which Dave and his team will attempt later this year.
0:57:26 > 0:57:28There's still a long way to go
0:57:28 > 0:57:31before we discover all of the secrets of the Swash Channel wreck,
0:57:31 > 0:57:34but due to the painstaking work of the archaeologists,
0:57:34 > 0:57:39she has now been revealed as one of the most important wrecks in our waters.
0:57:43 > 0:57:45This series has revealed the secret world
0:57:45 > 0:57:47that lies beneath Britain's seas.
0:57:47 > 0:57:50I've never seen anything like this,
0:57:50 > 0:57:52I'm just being surrounded by dorsal fins.
0:57:52 > 0:57:57Uncovering our magical marine life, mysterious wrecks,
0:57:57 > 0:58:00and our ever-changing relationship with the sea.
0:58:00 > 0:58:02These are what we're after.
0:58:02 > 0:58:04Look what else has come up as well!
0:58:04 > 0:58:08Our native waters are every bit as dramatic,
0:58:08 > 0:58:12colourful, and surprising
0:58:12 > 0:58:14as any of the oceans of the world.
0:58:14 > 0:58:17You can really get a sense of how fast they hit the water
0:58:17 > 0:58:19and stun those fish!
0:58:22 > 0:58:25Subtitles by Red Bee Media Ltd
0:58:25 > 0:58:28E-mail subtitling@bbc.co.uk