0:00:02 > 0:00:05They cover two thirds of our planet.
0:00:07 > 0:00:11They hold clues to the mysteries of our past.
0:00:13 > 0:00:16And they're vital for our future survival.
0:00:16 > 0:00:21But the secrets of our oceans have remained largely undiscovered
0:00:21 > 0:00:23until now.
0:00:23 > 0:00:25I am with a shark.
0:00:25 > 0:00:28Yes, yes!
0:00:28 > 0:00:32Explorer Paul Rose is leading a team of ocean experts
0:00:32 > 0:00:36on a series of underwater science expeditions.
0:00:37 > 0:00:41For a year the team has voyaged across the world
0:00:41 > 0:00:43to build up a global picture of our seas.
0:00:43 > 0:00:46We are doing some pretty uncharted research here.
0:00:46 > 0:00:49That is psychedelically purple!
0:00:49 > 0:00:54We're here to try and understand the earth's oceans and put them in a human scale.
0:00:58 > 0:01:00Our oceans are changing faster than ever.
0:01:00 > 0:01:03I've never seen ice like this before!
0:01:05 > 0:01:10There's never been a better time to explore the last true wilderness on earth.
0:01:21 > 0:01:23Looks good,
0:01:23 > 0:01:24perfect!
0:01:26 > 0:01:31The team is about to explore the sparkling blue waters of the Mediterranean sea.
0:01:33 > 0:01:35The remnant of an ancient ocean,
0:01:35 > 0:01:40this temperate sea is now home to over 700 varieties of fish
0:01:40 > 0:01:44and almost 10% of the world's marine species.
0:01:46 > 0:01:50Surrounded by the continents of Europe, Asia and Africa,
0:01:50 > 0:01:55its coastline is one of the most densely populated in the world.
0:01:56 > 0:01:58And the human pressure on this sea
0:01:58 > 0:02:03is magnified by 100 million visitors each year.
0:02:03 > 0:02:04Most people think of the Med
0:02:04 > 0:02:06as a holiday destination.
0:02:06 > 0:02:08It's hot, sunny,
0:02:08 > 0:02:09there's nice sandy beaches,
0:02:09 > 0:02:13but it's an ecosystem under pressure.
0:02:13 > 0:02:17Western civilisation developed around these shores
0:02:17 > 0:02:22but now human activity is threatening to ruin this sea.
0:02:22 > 0:02:26The Mediterranean has been critically important for so many thousands of years
0:02:26 > 0:02:28but the evidence is there.
0:02:28 > 0:02:30The Mediterranean is a shadow
0:02:30 > 0:02:32of what it once was.
0:02:33 > 0:02:37The team is here to explore the profound effect that man is having
0:02:37 > 0:02:40on these endangered waters.
0:02:42 > 0:02:46Quite a bit of life here but no large fish.
0:02:46 > 0:02:47On this expedition,
0:02:47 > 0:02:53environmentalist Philippe Cousteau investigates the delicate balance of marine life here
0:02:53 > 0:02:57and tries to protect one of man's most feared predators.
0:02:57 > 0:03:01The great white shark is definitely the holy grail, so to speak.
0:03:01 > 0:03:06And to search for them here in the Mediterranean, just fantastic!
0:03:08 > 0:03:12You actually can't see a way out. It is like you're surrounded on all sides.
0:03:13 > 0:03:18Marine biologist and oceanographer Tooni Mahto braves treacherous caves
0:03:18 > 0:03:22for evidence of some of the greatest changes to have shaped this sea.
0:03:23 > 0:03:25This cave is like a time capsule.
0:03:25 > 0:03:29This was once all dry land.
0:03:30 > 0:03:33Maritime archaeologist Dr Lucy Blue
0:03:33 > 0:03:38explores how the Mediterranean gave rise to one of Europe's first super-powers.
0:03:38 > 0:03:43The sea is often seen as that big dangerous expanse of blue
0:03:43 > 0:03:46that stops people moving around,
0:03:46 > 0:03:48but the Mediterranean is quite the opposite.
0:03:48 > 0:03:51It was a super-highway for millennia.
0:03:55 > 0:03:59The expedition will begin at the centre of the Mediterranean,
0:03:59 > 0:04:02in the waters between Italy and the island of Sicily,
0:04:02 > 0:04:03the Straits of Messina.
0:04:06 > 0:04:10The team is here to search for a prehistoric creature
0:04:10 > 0:04:12that's increasingly threatened.
0:04:12 > 0:04:16One of the largest predatory sharks in the world
0:04:16 > 0:04:18but one of the most rarely seen,
0:04:18 > 0:04:21the six gill shark.
0:04:21 > 0:04:23Typically, they're found in about 2,000 metres
0:04:23 > 0:04:25or in 6,000 or 7,000 feet of water.
0:04:25 > 0:04:28We assume they ride up in the middle of the night to feed,
0:04:28 > 0:04:32and then return back to the depths before the day.
0:04:32 > 0:04:34To have them here in about 40 metres of depth
0:04:34 > 0:04:37where we can get down and see them is super-rare.
0:04:37 > 0:04:41There's only a few places in the world where they've been found.
0:04:44 > 0:04:46If he's successful,
0:04:46 > 0:04:51expedition leader Paul will be one of only a few people ever to encounter this shark.
0:04:53 > 0:04:55Filming this vulnerable creature
0:04:55 > 0:04:59could give us a chance to learn more about this deep ocean animal
0:04:59 > 0:05:03facing threats from fishing, pollution and habitat destruction.
0:05:05 > 0:05:08We tend to think that obviously they've been filmed and studied loads
0:05:08 > 0:05:12but they haven't, so when I realised a glimpse is a success,
0:05:12 > 0:05:14it really puts pressure on tonight's dive.
0:05:18 > 0:05:19This rare opportunity
0:05:19 > 0:05:23is because of the peculiar underwater geography here.
0:05:26 > 0:05:28The Straits of Messina are a bottleneck
0:05:28 > 0:05:30connecting two deep sea basins.
0:05:30 > 0:05:34Tides and currents create upwellings,
0:05:34 > 0:05:37powerful surges of turbulent deep sea water,
0:05:37 > 0:05:40that are forced up and through this shallow narrow channel,
0:05:40 > 0:05:45dragging up rare creatures normally only found in the depths.
0:05:47 > 0:05:52The danger is that with these big overfalls and upwellings,
0:05:52 > 0:05:54that I'll get drawn to the surface quickly
0:05:54 > 0:05:59and it could be that I could come all the way to the surface
0:05:59 > 0:06:03and I can't afford to do that because I'd get decompression sickness.
0:06:03 > 0:06:04I'd get the bends.
0:06:04 > 0:06:08And it can be serious enough that I can end up, you know, tonight,
0:06:08 > 0:06:11I could do that dive, 40 metres, get blown to the surface
0:06:11 > 0:06:14and be in a wheelchair the rest of my life.
0:06:15 > 0:06:17Adding to the risk,
0:06:17 > 0:06:21this dive has to be made at night around the new moon.
0:06:21 > 0:06:24There are only a few nights when conditions are right,
0:06:24 > 0:06:28with tides strong enough to pull the six gill up from the deep.
0:06:31 > 0:06:36At midnight, Paul heads out into the inky waters.
0:06:38 > 0:06:43He will head the dive team with Philippe as his stand-by.
0:06:45 > 0:06:50I think this is an absolutely incredible opportunity to see a six gill shark
0:06:50 > 0:06:52because we know so little about these animals
0:06:52 > 0:06:57and the more evidence that we can gather about what they're doing down there, the better,
0:06:57 > 0:06:59the better for us to understand them,
0:06:59 > 0:07:02and also the better for us to hopefully protect them.
0:07:05 > 0:07:07Right Paul's good to go?
0:07:12 > 0:07:13Down we go.
0:07:13 > 0:07:15Good luck, mate.
0:07:19 > 0:07:21We're moving pretty fast actually.
0:07:21 > 0:07:24There's a real sense of purpose.
0:07:27 > 0:07:31Sharks are crucial to the health of our oceans.
0:07:31 > 0:07:37The six gill is almost identical to sharks from 200 million years ago,
0:07:37 > 0:07:40a living fossil that offers an insight
0:07:40 > 0:07:42into our prehistoric sea life.
0:07:44 > 0:07:47There's a lot of activity down here, we're swimming like the blazes.
0:07:50 > 0:07:56The night dive reveals some of the sea's nocturnal marine species
0:07:56 > 0:07:57like the moray eel.
0:08:02 > 0:08:07Paul swims by something that could entice a six gill into the area.
0:08:07 > 0:08:10It's not a shark but it's a beautiful octopus.
0:08:12 > 0:08:15Octopus, as well as fish and small sharks,
0:08:15 > 0:08:17are part of the six gill diet.
0:08:20 > 0:08:23But no sign of our shark, I'm afraid.
0:08:28 > 0:08:31The rescue boat is tracking the divers' lights,
0:08:31 > 0:08:37but diving at night in a strong current is a worry for dive supervisor Richard Bull.
0:08:37 > 0:08:40No matter how many times we've checked it,
0:08:40 > 0:08:45I'm always thinking, "What haven't we spotted, what is gonna go wrong?"
0:08:45 > 0:08:47When things go wrong when you're diving, it's bad.
0:08:47 > 0:08:50You know what I think the worst thing is? A missing diver.
0:08:53 > 0:08:56Paul still hasn't seen a shark.
0:08:56 > 0:08:59He's swimming against an exhausting three knot current
0:08:59 > 0:09:02so he is rapidly using up his air supply.
0:09:06 > 0:09:09Hang on, we can't see them for a second. Let me, uh...
0:09:09 > 0:09:16Suddenly the rescue boat loses sight of the divers forty metres below.
0:09:16 > 0:09:17Paul, surface?
0:09:17 > 0:09:19Kill all your lights, kill all the lights.
0:09:21 > 0:09:25To avoid decompression sickness as they ascend,
0:09:25 > 0:09:29Paul and his team need to breathe the pure oxygen the rescue boat is carrying.
0:09:30 > 0:09:33If we can't find them, the O2 tanks that they need for decompression,
0:09:33 > 0:09:35that are hanging under the boat,
0:09:35 > 0:09:39won't be there when they come up, so it's very dangerous.
0:09:39 > 0:09:42Mike Kasic is in charge of communications.
0:09:42 > 0:09:43Paul, surface?
0:09:47 > 0:09:48Paul, surface?
0:09:48 > 0:09:53Yes, just reporting, we've started to leave the bottom.
0:09:53 > 0:09:56We've lost you, we've lost you. So I need someone with lights
0:09:56 > 0:10:01to shine them to the surface so that we can kind of track you, OK?
0:10:02 > 0:10:04Roger, Roger.
0:10:13 > 0:10:16Keep your lights shining up, Paul.
0:10:23 > 0:10:26At last through the gloom, the divers' lights are spotted.
0:10:26 > 0:10:30Let's get some oxygen. Oxygen is going in now,
0:10:30 > 0:10:32and we're right over the top of them.
0:10:32 > 0:10:35We can see the cylinders, thanks guys.
0:10:35 > 0:10:40You know your heart skips a beat for a second but we found them.
0:10:44 > 0:10:46The relief that the team is safe
0:10:46 > 0:10:50is matched by frustration that they failed to find the six gill shark.
0:10:50 > 0:10:53What a disappointment.
0:10:53 > 0:10:57We have just swum our little legs off.
0:10:59 > 0:11:01You know, a bit tired from the exercise
0:11:01 > 0:11:04but disappointed really, blimey!
0:11:04 > 0:11:08I felt that we would find him, really did.
0:11:12 > 0:11:15The next night at midnight Paul dives again.
0:11:21 > 0:11:26Right, we're picking up the pace again.
0:11:27 > 0:11:31But after another exhausting swim, the dive ends.
0:11:31 > 0:11:36No sign of our shark, sorry guys.
0:11:45 > 0:11:48The team is beginning to understand
0:11:48 > 0:11:50why sightings of this shark are so rare.
0:11:53 > 0:11:56I look at the size of the strait
0:11:56 > 0:11:58and the small area that we can cover,
0:11:58 > 0:12:01although it feels like a whopping great big area,
0:12:01 > 0:12:03I realise it's a needle in a haystack job.
0:12:03 > 0:12:06Got one chance left tonight.
0:12:09 > 0:12:11It's the last night of the new moon
0:12:11 > 0:12:15when the tide could bring the six gill shark up from the depths.
0:12:15 > 0:12:19So Paul has pushed his equipment to the limit
0:12:19 > 0:12:21to give himself as much time as possible underwater.
0:12:23 > 0:12:27I've got the biggest cylinders I can carry and swim fast with,
0:12:27 > 0:12:28pumped to the absolute max.
0:12:28 > 0:12:32This is our opportunity to learn something and help study them
0:12:32 > 0:12:33so it means a lot.
0:12:36 > 0:12:38Six gills aren't aggressive to humans
0:12:38 > 0:12:42so to increase his chances of attracting one,
0:12:42 > 0:12:45Paul is attaching a bait bag to his dive belt.
0:12:47 > 0:12:51It's not that that great lump of tuna attracts a shark to bite you,
0:12:51 > 0:12:56but it grabs a lump of tuna and heads off into the deep dragging you with it,
0:12:56 > 0:12:59and that's when you've got to be prepared to get rid of it.
0:12:59 > 0:13:02Survival, it's a strong instinct isn't it?
0:13:03 > 0:13:08At 1:30 in the morning, the final dive begins.
0:13:17 > 0:13:20I do have to tell you, Philippe,
0:13:20 > 0:13:22it's absolutely perfect.
0:13:26 > 0:13:30We've slowed down a bit because we've come across a John Dory.
0:13:30 > 0:13:33It's a fantastic looking fish.
0:13:33 > 0:13:37Identifiable by the dark spot on the side of its body,
0:13:37 > 0:13:41this fish is another food source for predatory sharks.
0:13:44 > 0:13:47But we've got no time to waste, that's for sure.
0:13:48 > 0:13:51What are you seeing down there, over?
0:13:51 > 0:13:54Communications with Paul have failed.
0:13:54 > 0:13:58No I've got nothing, I don't even hear you speaking.
0:13:59 > 0:14:02Unaware that Philippe can't hear him,
0:14:02 > 0:14:05Paul presses on with his search.
0:14:05 > 0:14:07But I can't see anything.
0:14:07 > 0:14:10Where's the shark?
0:14:10 > 0:14:12Come on, baby.
0:14:12 > 0:14:15Where are you?
0:14:15 > 0:14:17Paul is down to his last ten minutes of air
0:14:17 > 0:14:20when he gets a signal from one of his dive team.
0:14:23 > 0:14:25Oh, wow!
0:14:25 > 0:14:28Surface, Paul. Surface, Paul.
0:14:28 > 0:14:31I am with a six gill shark.
0:14:33 > 0:14:35Can you believe this?!
0:14:40 > 0:14:45This is one of the largest predatory sharks in the world.
0:14:45 > 0:14:48It's a rare encounter with a mainly solitary animal
0:14:48 > 0:14:52that spends much of its life at the bottom of the sea,
0:14:52 > 0:14:55diving to depths of 2,000 metres.
0:15:14 > 0:15:17Look at those eyes. He's got those great green eyes.
0:15:19 > 0:15:24The eyes of deepwater sharks like the six gill can reflect light,
0:15:24 > 0:15:25enhancing their vision
0:15:25 > 0:15:28and allowing them to see in the gloom of the deep sea.
0:15:30 > 0:15:321, 2, 3, 4, 5, 6...
0:15:32 > 0:15:34yeah, there you go!
0:15:36 > 0:15:39Most sharks have evolved to have just five pairs of gills
0:15:39 > 0:15:41but the six gills on this shark
0:15:41 > 0:15:46make it similar to sharks dating from 200 million years ago.
0:15:46 > 0:15:48It's like swimming with a living dinosaur.
0:15:48 > 0:15:52The sixth gill is thought to help them breathe
0:15:52 > 0:15:55in the oxygen-depleted waters of the extreme depths.
0:15:55 > 0:15:58That's not the only primitive feature.
0:15:58 > 0:16:00Its teeth and the structure of the jaw
0:16:00 > 0:16:05mean it closely resembles fossils of sharks from the Jurassic period.
0:16:29 > 0:16:32Six gill sharks spend most of their life at extreme depths
0:16:32 > 0:16:34where they can't be reached,
0:16:34 > 0:16:37so rare film like this will help scientists to study them.
0:16:41 > 0:16:43Ah blimey, there he goes.
0:16:53 > 0:16:55Philippe still doesn't know what's happened
0:16:55 > 0:16:58but as the divers begin to ascend, contact is restored.
0:16:58 > 0:17:02OK Paul, surface. What did you see down there? Over.
0:17:02 > 0:17:05We're now, uh...
0:17:05 > 0:17:09slowly coming up to our first stop,
0:17:09 > 0:17:12but we've all got big grins!
0:17:12 > 0:17:13Paul, surface, uh...
0:17:13 > 0:17:15Confirm, did you see a shark?
0:17:15 > 0:17:17Did you see a six gill, over?
0:17:17 > 0:17:20Roger, Roger. Saw a six gill shark!
0:17:20 > 0:17:23And he was a beauty!
0:17:23 > 0:17:26And it was a wonderful experience,
0:17:26 > 0:17:29we were in contact for five or ten minutes.
0:17:29 > 0:17:31Five or ten minutes?!
0:17:31 > 0:17:33Of course, the five or ten minutes the comms were out!
0:17:33 > 0:17:38I began to wonder if we'd see him before we ran out of air.
0:17:38 > 0:17:42- That's brilliant! - Guys, it was worth the effort,
0:17:42 > 0:17:44totally worth the effort.
0:17:46 > 0:17:48That is fantastic!
0:17:48 > 0:17:53Paul, my man, how was it?
0:17:53 > 0:17:55You'll never believe it.
0:17:55 > 0:17:58We just swam down and just when we were thinking,
0:17:58 > 0:18:01burning up too much air trying to find this,
0:18:01 > 0:18:04and then he just came straight in.
0:18:04 > 0:18:06Just as smooth and as easy as you like!
0:18:09 > 0:18:14Sharks play a crucial role as predators in our seas and oceans,
0:18:14 > 0:18:16weeding out the sick and injured,
0:18:16 > 0:18:18but numbers are decreasing rapidly.
0:18:21 > 0:18:25Later in the expedition, the team will investigate
0:18:25 > 0:18:29how another shark could be at risk in this fast-changing sea.
0:18:36 > 0:18:40The Mediterranean is famous for its clear blue water,
0:18:40 > 0:18:43but that could be a sign of its vulnerability.
0:18:44 > 0:18:48Clear water indicates low levels of plankton,
0:18:48 > 0:18:51a crucial source of food in the sea.
0:18:51 > 0:18:56So Paul and oceanographer Tooni are using a secchi disc,
0:18:56 > 0:19:00a standard oceanographic tool, to measure the clarity of the water.
0:19:00 > 0:19:01- OK, ready?- Yeah.
0:19:04 > 0:19:08In nutrient-rich waters the disc would disappear within a few metres.
0:19:08 > 0:19:10There we go.
0:19:10 > 0:19:12So there's nine.
0:19:12 > 0:19:15- Still seeing it?- Yeah, totally.
0:19:15 > 0:19:17Eleven.
0:19:17 > 0:19:19That's the end of it, we can't go any deeper!
0:19:19 > 0:19:22- It's as clear now as it was at one metre.- That's amazing.
0:19:23 > 0:19:26The clearer the water, the less plankton there is.
0:19:26 > 0:19:28That means we're in very low nutrient conditions.
0:19:28 > 0:19:32That is essentially why the Mediterranean is so blue.
0:19:32 > 0:19:35There's no microscopic plant or animal activity
0:19:35 > 0:19:40which means there's nothing to suck the light out of the water column.
0:19:43 > 0:19:47The Mediterranean has some of the lowest nutrient levels of any sea.
0:19:47 > 0:19:50This restricts how much can live here,
0:19:50 > 0:19:54as there's a limited amount of food,
0:19:54 > 0:19:55making it a delicate ecosystem
0:19:55 > 0:19:58particularly vulnerable to human activity.
0:20:05 > 0:20:10To find out just what marine life the Med is capable of supporting,
0:20:10 > 0:20:13the team's heading twenty-five miles south-west of Sicily,
0:20:13 > 0:20:16to one place that should be full of life -
0:20:16 > 0:20:18an enormous underwater volcano.
0:20:19 > 0:20:21It's 8:30 and we're on site.
0:20:21 > 0:20:24We've travelled all night and woke up this morning
0:20:24 > 0:20:30to see that we were in position and we've found the summit of the volcano
0:20:30 > 0:20:33which is right under the boat right now.
0:20:34 > 0:20:37Ferdinandea is over four hundred metres high
0:20:37 > 0:20:42and has a base that measures 750 square kilometres.
0:20:43 > 0:20:47Its tip is just eight metres from the surface.
0:20:49 > 0:20:51Many volcanoes were created
0:20:51 > 0:20:56as a result of the Mediterranean's tectonic plates colliding during its formation.
0:20:56 > 0:21:00Some breached the surface to form islands,
0:21:00 > 0:21:05which is exactly what happened to Ferdinandea in the 19th century
0:21:05 > 0:21:07as this contemporary painting depicts.
0:21:08 > 0:21:13It turns out when it was up, in 1831, it was actually a proper island.
0:21:13 > 0:21:18It was 60 metres high and something like four kilometres circumference,
0:21:18 > 0:21:19just under three miles round.
0:21:19 > 0:21:24But it turns out that it only lasted six months, just magma,
0:21:24 > 0:21:26and it just all quickly turned to ash
0:21:26 > 0:21:29and a few big seas and rain and general weather,
0:21:29 > 0:21:31and it demolished the top and once it got low,
0:21:31 > 0:21:33the sea knocked it back.
0:21:36 > 0:21:40Ferdinandea is now completely underwater once again,
0:21:40 > 0:21:43one of thousands of seamounts around the world
0:21:43 > 0:21:46which are magnets for marine life.
0:21:46 > 0:21:50So the team goes to find out what's living here.
0:21:50 > 0:21:54This volcano was created at the collision point
0:21:54 > 0:21:56of the African and European plates.
0:21:56 > 0:21:58Check out the ridges.
0:21:58 > 0:22:01It's very strange how there's a rippling effect
0:22:01 > 0:22:04in the black volcanic basalt.
0:22:04 > 0:22:08The ridges are caused by the speed of the water current
0:22:08 > 0:22:09that passes over them.
0:22:11 > 0:22:13This fertile volcanic sand
0:22:13 > 0:22:20allows the millions of microscopic plant and animal larvae that float in the open sea, to grow here.
0:22:20 > 0:22:23Seamounts are biodiversity hotspots
0:22:23 > 0:22:26because they provide organisms with a place to land and settle
0:22:26 > 0:22:31in an otherwise featureless flat ocean.
0:22:33 > 0:22:36As deep water hits these underwater mountains,
0:22:36 > 0:22:39it rises, bringing nutrients from the seabed,
0:22:39 > 0:22:40creating a rich feeding ground.
0:22:43 > 0:22:45These places, they've become like an oasis
0:22:45 > 0:22:48because they've got such deep waters all around us
0:22:48 > 0:22:51and this thing coming right up in this beautiful light zone
0:22:51 > 0:22:54attracts an abundance of life.
0:22:56 > 0:23:01Marine life uses seamounts as habitats, as spawning grounds,
0:23:01 > 0:23:04even as stepping stones while it travels around the sea.
0:23:04 > 0:23:07Lucy and environmentalist Philippe
0:23:07 > 0:23:10should find the summit teeming with life.
0:23:11 > 0:23:14There are lots of small schooling fish which is a good sign.
0:23:14 > 0:23:16Oh, and a sea urchin!
0:23:16 > 0:23:22Sea urchins just love all the algae that grows in here.
0:23:23 > 0:23:28But it soon becomes apparent something crucial is missing.
0:23:28 > 0:23:31Quite a bit of life here but no large fish.
0:23:33 > 0:23:36There's no sign of the open water fish
0:23:36 > 0:23:40like sardines, tuna and grouper that should be here.
0:23:40 > 0:23:44This is essentially an artificial reef in a big void space
0:23:44 > 0:23:48so all the little fish come here because they've got places to hide.
0:23:49 > 0:23:52And the little fish then attract the big fish
0:23:52 > 0:23:54but it also attracts the fishermen,
0:23:54 > 0:23:59so I'm not surprised to see not a lot of big fish here in this area
0:23:59 > 0:24:03because most likely the fishermen come here frequently.
0:24:05 > 0:24:09Fishing has been an integral part of Mediterranean culture
0:24:09 > 0:24:10for thousands of years.
0:24:10 > 0:24:14Until recently, it was a largely sustainable industry.
0:24:16 > 0:24:23However, since 1970 fishing in the Med has increased by almost 50%.
0:24:23 > 0:24:29Conservationists now warn the entire sea is endangered.
0:24:29 > 0:24:33The problem with the Med is because technology has advanced so swiftly
0:24:33 > 0:24:35in the past 50 or 60 years,
0:24:35 > 0:24:38and because it's such an enclosed area,
0:24:38 > 0:24:42this is the place where the technological advances are going to have the most impact.
0:24:46 > 0:24:49That impact is particularly felt
0:24:49 > 0:24:52by an iconic species of the Mediterranean -
0:24:52 > 0:24:55the Atlantic blue fin tuna.
0:24:55 > 0:24:58They're pretty incredible animals.
0:24:58 > 0:25:00They're fast, one of the few fish that are warm-blooded,
0:25:00 > 0:25:03they're very complex, very interesting animals,
0:25:03 > 0:25:05they're ocean-roaming all over the world,
0:25:05 > 0:25:07and they're very highly prized.
0:25:09 > 0:25:13The value of the estimated total blue fin tuna catch in the Med
0:25:13 > 0:25:15is around £400 million.
0:25:15 > 0:25:19This has triggered the rise in industrial fishing.
0:25:22 > 0:25:26Philippe and marine biologist Tooni are heading off to investigate
0:25:26 > 0:25:30one of the more recent developments in the harvesting of this sea -
0:25:30 > 0:25:31a tuna farm.
0:25:34 > 0:25:37It almost looks like a kind of rubberised pen
0:25:37 > 0:25:41you'd see at an amusement park for people to go splash around in.
0:25:41 > 0:25:43This is going to be full of tuna.
0:25:43 > 0:25:45And ironically enough,
0:25:45 > 0:25:49this is pretty much the only place I'm going to see such large schools.
0:25:49 > 0:25:51- Any more.- Any more.
0:25:51 > 0:25:55There are now over 40 offshore tuna farms in the Mediterranean.
0:25:55 > 0:25:58One, go for it.
0:25:58 > 0:25:59Go for it.
0:26:05 > 0:26:09Just look at the size of the net, it's huge.
0:26:09 > 0:26:13In one way I was really looking forward to seeing these tuna because
0:26:13 > 0:26:16I've never gotten to see them before in the wild.
0:26:16 > 0:26:22- But seeing them swimming in circle after circle, over and over...- Yeah.
0:26:43 > 0:26:4720,000 to 30,000 tons are caught each summer in vast drag nets,
0:26:47 > 0:26:49and towed to the tuna farms.
0:26:50 > 0:26:54Well, these tuna have just recently been caught.
0:26:54 > 0:26:57They'll be fed regularly to fatten them up
0:26:57 > 0:27:00and then once they've reached a certain size,
0:27:00 > 0:27:02about 200 to 300 kilograms,
0:27:02 > 0:27:06they'll be taken to the mainland where they'll be shipped to Japan.
0:27:06 > 0:27:12These wild blue fin tuna migrated here from the Atlantic Ocean
0:27:12 > 0:27:15to spawn in the warmer waters.
0:27:15 > 0:27:19They swim with their mouths open to force water over their gills.
0:27:19 > 0:27:21If they stop, they suffocate.
0:27:21 > 0:27:25Look at that blue stripe.
0:27:25 > 0:27:27That's what gives them their name blue fin tuna.
0:27:27 > 0:27:29It's a beautiful blue colour.
0:27:32 > 0:27:34This farm operates within the law
0:27:34 > 0:27:38but conservationists believe the high value of this tuna
0:27:38 > 0:27:41means some fishermen are exceeding quota limits.
0:27:41 > 0:27:44What's more, some are even flouting restrictions
0:27:44 > 0:27:46on the size of the tuna they catch.
0:27:48 > 0:27:53The fear is that more and more tuna farms are catching juveniles.
0:27:53 > 0:27:55Yeah, this is depleting the population
0:27:55 > 0:27:58before they even have a chance to procreate
0:27:58 > 0:27:59and start the next generation.
0:27:59 > 0:28:03And that's pushing the blue fin population here to the brink of extinction.
0:28:06 > 0:28:11Scientists believe that as much as 20,000 tons of blue fin tuna
0:28:11 > 0:28:15are caught illegally in the Mediterranean every year.
0:28:15 > 0:28:17The Med's most iconic fish,
0:28:17 > 0:28:20and the traditional fisheries it once supported,
0:28:20 > 0:28:22are now close to collapse.
0:28:24 > 0:28:27It doesn't just have an implication for the Mediterranean.
0:28:27 > 0:28:29It has an implication for the Atlantic
0:28:29 > 0:28:31because they're a migratory species.
0:28:31 > 0:28:34For the survival of the Mediterranean economy
0:28:34 > 0:28:36and survival of Mediterranean traditions
0:28:36 > 0:28:39that have been in place for thousands of years,
0:28:39 > 0:28:42you have to maintain a population of that species
0:28:42 > 0:28:43and that isn't happening.
0:28:46 > 0:28:50The exploitation of this sea is no new phenomenon.
0:28:50 > 0:28:54Man's influence has been felt here for millennia.
0:28:54 > 0:28:57Some of the greatest civilisations in our history
0:28:57 > 0:29:01have used the Mediterranean to their advantage.
0:29:03 > 0:29:07Maritime archaeologist Dr Lucy Blue
0:29:07 > 0:29:09has worked in the Med for much of her career,
0:29:09 > 0:29:12exploring how this sea is uniquely important
0:29:12 > 0:29:14in the development of western civilisation.
0:29:15 > 0:29:19You know this is where cultures developed, around these shores.
0:29:19 > 0:29:22The sea, in this instance more than anywhere else in the world,
0:29:22 > 0:29:25facilitated the communications and the development
0:29:25 > 0:29:27of these civilisations.
0:29:28 > 0:29:32The Romans ruled this sea over 2,000 years ago
0:29:32 > 0:29:36and became one of humanity's first superpowers.
0:29:36 > 0:29:42Lucy has brought the team to the Egadi Islands to the west of Sicily.
0:29:42 > 0:29:45She wants to search the wreck of a Roman cargo ship
0:29:45 > 0:29:48for any clues to what was being traded,
0:29:48 > 0:29:52and how far these routes stretched across the Mediterranean.
0:29:55 > 0:29:59It's 1st century BC so it's the early part of the Roman period
0:29:59 > 0:30:02where they've just taken Sicily over
0:30:02 > 0:30:04so it's about development and expansion.
0:30:06 > 0:30:10They're going to dive to just one of hundreds Roman wrecks
0:30:10 > 0:30:12that have been discovered in the Med,
0:30:12 > 0:30:15clear evidence of the scale of traffic
0:30:15 > 0:30:17around this sea in ancient times.
0:30:19 > 0:30:22OK, so we're gonna moor up to the buoy that you can see over there
0:30:22 > 0:30:24- where the other boat is.- Yeah.
0:30:24 > 0:30:26And there's a shotline there. It goes down to 12 metres
0:30:26 > 0:30:29and basically that just slips down quite gradually
0:30:29 > 0:30:32to about 24 metres.
0:30:32 > 0:30:35Is that good? You're clear. Clear behind.
0:30:35 > 0:30:37On your mark, clear.
0:30:45 > 0:30:47The wooden structure of the shipwreck
0:30:47 > 0:30:49has long since disintegrated.
0:30:49 > 0:30:52What remains is some of the cargo it carried,
0:30:52 > 0:30:56a mound of amphorae, enormous ceramic containers.
0:31:02 > 0:31:06Just getting a first glimpse of the amphorae on the sea bed
0:31:06 > 0:31:09and it's really quite remarkable,
0:31:09 > 0:31:13and although I have worked on a number of shipwrecks over the years,
0:31:13 > 0:31:17I have never actually seen such a large number of amphorae
0:31:17 > 0:31:19concentrated in one spot.
0:31:21 > 0:31:25The wreck dates from around the 1st century BC.
0:31:25 > 0:31:28That's over 2,000 years old.
0:31:42 > 0:31:46Now that's a fairly intact one, there.
0:31:46 > 0:31:49But what were the Romans trading?
0:31:49 > 0:31:52Shall I grab that end?
0:31:52 > 0:31:53What have you got?
0:31:56 > 0:31:58I've got 120.
0:31:58 > 0:32:00It's huge.
0:32:00 > 0:32:04From the shapes and the fact that they were lined with bitumen or pitch,
0:32:04 > 0:32:07they likely carried wine.
0:32:08 > 0:32:14Probably would have carried about 20, 25 litres of wine.
0:32:14 > 0:32:15You can see the shape of them.
0:32:15 > 0:32:19It's perfectly made to slot into the hull of a vessel.
0:32:19 > 0:32:22This is how they would have stored them,
0:32:22 > 0:32:26sort of one on top of the other in the hull of a Roman merchantman.
0:32:28 > 0:32:31Having found out that these amphorae are likely to have carried wine,
0:32:31 > 0:32:37Lucy now needs to look for any clues that might reveal who produced it.
0:32:37 > 0:32:42There's one that has the names of the family that produced the wine.
0:32:42 > 0:32:44"Papia".
0:32:45 > 0:32:46Based in southern Italy,
0:32:46 > 0:32:50the Papia family were a powerful dynasty of winemakers
0:32:50 > 0:32:53who exported it around the Mediterranean.
0:32:53 > 0:32:57It's likely that they were transporting them from Sicily
0:32:57 > 0:32:59maybe even to north Africa.
0:32:59 > 0:33:05This would have been part of the general trade in wine and olive oil,
0:33:05 > 0:33:08garum - which is a fish paste -
0:33:08 > 0:33:12that was being conducted around the Mediterranean at this time.
0:33:15 > 0:33:18This is a record of a trade that linked two continents,
0:33:18 > 0:33:21and the scale of this operation
0:33:21 > 0:33:24shows how effectively the Romans established trading routes
0:33:24 > 0:33:26around the Mediterranean.
0:33:26 > 0:33:29There are about forty amphorae here,
0:33:29 > 0:33:32but these are only a fraction of the original cargo.
0:33:34 > 0:33:37There used to be about 400 to 500
0:33:37 > 0:33:39but these have been taken by looters.
0:33:39 > 0:33:42It's a big problem in the Mediterranean.
0:33:46 > 0:33:48Treasure hunters have damaged and stolen
0:33:48 > 0:33:52many of the rich but fragile historical remains
0:33:52 > 0:33:53that scatter the floor of the Med.
0:33:56 > 0:33:59To protect what remains of these amphorae,
0:33:59 > 0:34:02this underwater archaeological site
0:34:02 > 0:34:06is being monitored 24 hours a day by CCTV.
0:34:13 > 0:34:16The pictures are fed to the nearby island of Favignana
0:34:16 > 0:34:18where they're monitored by police.
0:34:18 > 0:34:21Buon giorno, possiamo guardare?
0:34:21 > 0:34:25- Prego.- Grazie. - What was that?
0:34:25 > 0:34:28Just asked permission, want to have a little respect.
0:34:28 > 0:34:30- Ooh!- We've got some visitors.
0:34:30 > 0:34:33There's Paul right in front of the camera. And there's Lucy.
0:34:34 > 0:34:36I think this whole project is so unique,
0:34:36 > 0:34:40the fact that they're very interested in the conservation of these relics.
0:34:40 > 0:34:43It's kind of sad that they had to in the first place
0:34:43 > 0:34:45but it's very cool that they do it.
0:34:45 > 0:34:47Since CCTV was installed,
0:34:47 > 0:34:51not a single Roman amphora has been stolen.
0:34:51 > 0:34:55The cameras protect what remains of this valuable site,
0:34:55 > 0:35:01a record of how the Mediterranean sea enabled civilisations to expand.
0:35:07 > 0:35:09For the team's next mission,
0:35:09 > 0:35:12Paul and Tooni are heading off to Mallorca
0:35:12 > 0:35:14to look much further back in time.
0:35:14 > 0:35:19They'll be diving underground to search for evidence of huge changes
0:35:19 > 0:35:23which transformed the whole Mediterranean,
0:35:23 > 0:35:27changes that helped bring people here in the first place.
0:35:37 > 0:35:40Mallorca lies in the western Mediterranean.
0:35:40 > 0:35:46Beneath the island's east coast is a vast network of flooded caves.
0:35:48 > 0:35:50This cave system is connected to the sea
0:35:50 > 0:35:54but Paul and Tooni must drive several kilometres inland
0:35:54 > 0:35:56to reach the entrance.
0:35:57 > 0:36:02In these flooded caves are unusual formations that you can only see,
0:36:02 > 0:36:06apparently you can pick them up in the Bahamas and a few other spots
0:36:06 > 0:36:12but this is a really rare opportunity to learn more about the Med.
0:36:12 > 0:36:15It's probably the most dangerous diving we're gonna do on this!
0:36:15 > 0:36:19Yeah, that's going to make me feel better. Thanks mate(!)
0:36:25 > 0:36:27- Here we go.- That looks like a cave.
0:36:27 > 0:36:29Doesn't fill me with joy, it has to be said.
0:36:29 > 0:36:31It doesn't look very inviting.
0:36:31 > 0:36:35Paul and oceanographer Tooni will be searching for proof
0:36:35 > 0:36:40of when Mediterranean sea levels dropped many thousands of years ago,
0:36:40 > 0:36:43changing the coastline and creating the ideal conditions
0:36:43 > 0:36:45for people to spread and settle.
0:36:47 > 0:36:52They'll have to brave a perilous section of flooded caves
0:36:52 > 0:36:57and though they're both trained cave divers, this is a dangerous task.
0:36:57 > 0:37:01There's a definite sense within me that this is a risky dive.
0:37:01 > 0:37:03As soon as you can't get to the surface,
0:37:03 > 0:37:06there's a lot of opportunities for things to go wrong.
0:37:09 > 0:37:15They are hoping to examine rare rock formations deep inside the earth.
0:37:26 > 0:37:31The dive begins with a claustrophobic entrance way.
0:37:34 > 0:37:40Here we go. The trick here, Tooni, is going to be head first for sure.
0:37:40 > 0:37:44Just have to take our time as we go through this squeeze.
0:37:45 > 0:37:48The visibility has gone to next to nothing.
0:37:50 > 0:37:52Very, very, very tight indeed, this.
0:37:52 > 0:37:57You couldn't possibly go through much smaller of a space.
0:38:00 > 0:38:06One hand at a time, one hand at a time.
0:38:07 > 0:38:09It goes down as well.
0:38:09 > 0:38:14Tooni and Paul dive further and further down below ground
0:38:14 > 0:38:15into the cave system.
0:38:17 > 0:38:22Kind of a brutal start this, no visibility and very cold.
0:38:26 > 0:38:29As they travel deeper into the network,
0:38:29 > 0:38:31they reach a mysterious water haze.
0:38:34 > 0:38:37Here we go, halocline coming up, Tooni, look.
0:38:39 > 0:38:44This haze, or halocline, is caused by light rays diffracting
0:38:44 > 0:38:48as they pass through the different densities of clearer fresh water,
0:38:48 > 0:38:49and denser salt water.
0:38:49 > 0:38:54It's the first sign these inland caves are connected to the sea.
0:38:55 > 0:38:58I love the fact that you've got fresh water above
0:38:58 > 0:39:00and sea water below,
0:39:00 > 0:39:03and then you get this crazy kind of lime cordial effect
0:39:03 > 0:39:04where the two meet.
0:39:04 > 0:39:10I've never been able to SEE density before.
0:39:10 > 0:39:12Physics in action.
0:39:14 > 0:39:17Coming out of that halocline, look how clear it is now.
0:39:18 > 0:39:21Oh, that is beautiful!
0:39:29 > 0:39:34The divers emerge into the crystal clear water of an enormous cavern.
0:39:36 > 0:39:40Wow, Tooni, look at the size of this room.
0:39:40 > 0:39:42This is just incredible!
0:39:54 > 0:39:58I'd always fancied being an astronaut
0:39:58 > 0:40:00but maybe this is as close as I'm ever gonna get.
0:40:00 > 0:40:02Instead of outer space,
0:40:02 > 0:40:05it's like the cave divers use that word, "inner space",
0:40:05 > 0:40:07and it's very true.
0:40:11 > 0:40:15Deep inside the earth, they've found what they've been looking for,
0:40:15 > 0:40:19spectacular sculptural rock formations,
0:40:19 > 0:40:22that shouldn't even be here.
0:40:22 > 0:40:25We've come underwater here, below sea level,
0:40:25 > 0:40:30and yet we're seeing these stalagmites on the bottom
0:40:30 > 0:40:32and the stalactites from the ceiling
0:40:32 > 0:40:34which means that this cave was once dry
0:40:34 > 0:40:38because those things only form in dry caves.
0:40:38 > 0:40:42These majestic structures have formed over time
0:40:42 > 0:40:46by mineral-rich water dripping into dry caves.
0:40:46 > 0:40:48To find them in this flooded cave
0:40:48 > 0:40:53is proof that the sea level was once much lower than it is today.
0:40:56 > 0:41:00These rare bulbous formations around the stalactites and stalagmites,
0:41:00 > 0:41:03found almost nowhere else on earth,
0:41:03 > 0:41:06can reveal when the sea level changed.
0:41:06 > 0:41:09This bulge was formed when the sea level was here.
0:41:09 > 0:41:12Lapping water deposited minerals
0:41:12 > 0:41:16which created this blancmange-like structure.
0:41:16 > 0:41:19By dating these mineral deposits,
0:41:19 > 0:41:22scientists can build up a chronological record
0:41:22 > 0:41:25of changing sea levels in the Med.
0:41:25 > 0:41:27Sea levels have been going up and down
0:41:27 > 0:41:29over hundreds of thousands of years.
0:41:34 > 0:41:38This evidence proves that 60,000 to 80,000 years ago,
0:41:38 > 0:41:40the Mediterranean sea was shallower.
0:41:42 > 0:41:45Lower sea levels exposed new ground
0:41:45 > 0:41:48and created land bridges between islands.
0:41:48 > 0:41:52This allowed early humans who'd migrated out of Africa
0:41:52 > 0:41:57to move around the Mediterranean, settling on its coasts and islands.
0:41:58 > 0:42:00This cave is like a time capsule.
0:42:00 > 0:42:02It proves how much the Med has changed
0:42:02 > 0:42:03and that's had a huge influence.
0:42:09 > 0:42:12The Mediterranean has been host to humanity
0:42:12 > 0:42:14for hundreds of thousands of years.
0:42:18 > 0:42:21Today over 150 million people live around its shores.
0:42:21 > 0:42:24That number almost doubles in the summer
0:42:24 > 0:42:27with the influx of holidaymakers.
0:42:29 > 0:42:32Pollution, fishing and coastal development
0:42:32 > 0:42:35are putting enormous stress on these fragile waters,
0:42:35 > 0:42:37threatening marine life.
0:42:40 > 0:42:44Rare species are most likely to suffer.
0:42:44 > 0:42:46And one of the Med's most endangered
0:42:46 > 0:42:51is so elusive many are surprised to learn it's here at all.
0:42:51 > 0:42:53Philippe wants to investigate
0:42:53 > 0:42:58why the Mediterranean is home to one of our most feared predators,
0:42:58 > 0:42:59the great white shark.
0:43:08 > 0:43:10People think oh, Jaws,
0:43:10 > 0:43:13sharks are these monsters of the ocean coming to eat us,
0:43:13 > 0:43:16but sharks are critical to the health of the marine environment
0:43:16 > 0:43:18because they're apex predators.
0:43:18 > 0:43:21They have a perfect place in their ecosystem,
0:43:21 > 0:43:23balancing and keeping it healthy.
0:43:23 > 0:43:25They are...beautiful.
0:43:28 > 0:43:31These great whites were filmed off South Africa.
0:43:31 > 0:43:33They're most likely to be found there,
0:43:33 > 0:43:36or off California and Australia.
0:43:36 > 0:43:41The clear waters of the Med might seem an unlikely habitat for this predatory shark
0:43:41 > 0:43:43because of the limited food supply.
0:43:45 > 0:43:48But there have been rare sightings
0:43:48 > 0:43:51to suggest the great white is living here.
0:43:54 > 0:43:59This extraordinary footage was recorded ten years ago
0:43:59 > 0:44:02by a fisherman on holiday in the Med with his son.
0:44:05 > 0:44:09It shows a great white shark circling the fisherman's boat
0:44:09 > 0:44:12before tearing chunks from a small fresher shark he'd caught.
0:44:21 > 0:44:25But sightings like this are extremely uncommon.
0:44:25 > 0:44:28There is some video of great whites in the past
0:44:28 > 0:44:31but any evidence that we can gather
0:44:31 > 0:44:36to prove that great white sharks live in the Mediterranean
0:44:36 > 0:44:39would help us to protect these incredible creatures.
0:44:41 > 0:44:44To investigate why great whites could be here,
0:44:44 > 0:44:47the team is heading to the middle of the Sicilian channel,
0:44:47 > 0:44:50to the tiny island of Lampedusa.
0:44:54 > 0:44:58This must be him, he's headed right for us.
0:44:58 > 0:45:01That is my man! All right, finally!
0:45:01 > 0:45:03- Buon giorno!- Good morning!
0:45:03 > 0:45:06- How are you, man?- OK, great!
0:45:06 > 0:45:09They'll be working with patron of the Shark Trust
0:45:09 > 0:45:13and world expert on great whites in the Med, Ian Ferguson.
0:45:13 > 0:45:16We're ready for you.
0:45:17 > 0:45:20Ian's been looking for the great white here for over fifteen years
0:45:20 > 0:45:24and he's convinced there's a pattern to the occasional sightings.
0:45:24 > 0:45:26Have the sharks that have been caught
0:45:26 > 0:45:30in this particular month in this area just been pure one-offs,
0:45:30 > 0:45:32or are they actually here for a reason?
0:45:32 > 0:45:34And my longstanding hypothesis
0:45:34 > 0:45:36is that the animals are here,
0:45:36 > 0:45:38and the reason is to give birth.
0:45:40 > 0:45:42The Sicilian channel is the only location
0:45:42 > 0:45:45in the entire eastern Atlantic region
0:45:45 > 0:45:48where both pregnant and new-born great whites have been sighted.
0:45:48 > 0:45:51Yeah, we think it's about three...
0:45:51 > 0:45:54Ian believes this could be one of only a few nursery areas
0:45:54 > 0:45:57identified anywhere for these endangered sharks.
0:45:57 > 0:45:59It's an area of great importance,
0:45:59 > 0:46:02it's obviously a very important habitat for them
0:46:02 > 0:46:05and we need to get to understand why is this area so important
0:46:05 > 0:46:08and what can we do to protect the sharks.
0:46:11 > 0:46:14So what might make this a suitable breeding ground?
0:46:14 > 0:46:18The harbour is right there. The proposal is to come round here,
0:46:18 > 0:46:21a deep dive there on the wall - you know, 40 metres -
0:46:21 > 0:46:23to check out the habitat, really.
0:46:23 > 0:46:29The idea behind this is that this could be potential for feeding,
0:46:29 > 0:46:32- this is what great whites like to eat.- Sure.
0:46:36 > 0:46:38Tooni and Lucy dive to look for any evidence
0:46:38 > 0:46:42that this might be a great white nursery.
0:46:43 > 0:46:47Now keep your eyes peeled out there for large pelagics.
0:46:47 > 0:46:52If we're going to see them anywhere, we should be seeing them here.
0:46:53 > 0:46:56Compared to other parts of the Med,
0:46:56 > 0:46:59the warm water of the Sicilian channel is rich in nutrients.
0:46:59 > 0:47:03This should attract pelagic or open water fish,
0:47:03 > 0:47:07as well as dolphins and turtles that great whites feed on.
0:47:08 > 0:47:12Lucy, there's a shoal of damsel fish just here.
0:47:12 > 0:47:15They're very, very territorial fish,
0:47:15 > 0:47:19so this seems to be quite a productive area we're in.
0:47:21 > 0:47:23Oh, that's a big grouper!
0:47:24 > 0:47:27Bottom-dwelling fish like this
0:47:27 > 0:47:30are a typical part of the diet of juvenile great whites.
0:47:32 > 0:47:35Because this is such a great place for fish,
0:47:35 > 0:47:37it's also a great place for sharks.
0:47:39 > 0:47:43And there's further evidence to support Ian's theory.
0:47:43 > 0:47:48This shallow shelf is typical of the habitat young great whites need.
0:47:48 > 0:47:52It keeps away predators like blue and mako sharks
0:47:52 > 0:47:55that don't hunt in shallow waters.
0:47:58 > 0:48:02But at the surface, events take a turn for the worse.
0:48:05 > 0:48:08I've just been to see the captain. There's gales forecast.
0:48:08 > 0:48:11It'll be 25 knots-plus, which is...
0:48:11 > 0:48:13you know, at sea, isn't the worst weather,
0:48:13 > 0:48:17but for what we've got in mind, it's never going to work.
0:48:19 > 0:48:22With the wind picking up,
0:48:22 > 0:48:25it's urgent to get Tooni and Lucy back on board.
0:48:25 > 0:48:28All divers, all divers, surface.
0:48:28 > 0:48:31We need to get out of the water as soon as possible.
0:48:44 > 0:48:48The wind's really picking up now, the wind's really picking up now.
0:48:48 > 0:48:50So we've called Tooni and Lucy back early.
0:48:50 > 0:48:53We've got the main engines running now.
0:48:53 > 0:48:58We're going to get the guys in, and run for Lampedusa, fast.
0:49:02 > 0:49:07The storm's an unwelcome delay to their investigation of the great white in the Med.
0:49:08 > 0:49:11- It's a totally different sea out there, isn't it?- Yeah.
0:49:11 > 0:49:14It's like the North Sea and it's getting rougher by the minute.
0:49:26 > 0:49:29Next day, the storm has subsided...
0:49:29 > 0:49:31Keep pulling on yours, Philippe.
0:49:31 > 0:49:35..and the team decide on a last, hugely ambitious attempt to gather direct evidence,
0:49:35 > 0:49:37laying a bait trail of chum -
0:49:37 > 0:49:42pulped oily fish - to try and attract a great white to the boat.
0:49:42 > 0:49:46We're going to deploy the most fantastic shark cage on the planet,
0:49:46 > 0:49:50get some people in there, chum and chum and chum.
0:49:50 > 0:49:53See if we can find some great whites.
0:49:57 > 0:50:00Everyone's aware it's a long shot.
0:50:00 > 0:50:02They now only have a few days
0:50:02 > 0:50:07to create a chum slick big and nasty enough to attract a great white.
0:50:11 > 0:50:14- You got it?- Yeah, bung it, bung it.
0:50:14 > 0:50:17Give it a shake to start it off.
0:50:19 > 0:50:22Bung it.
0:50:22 > 0:50:25- Just revolting. - It's horrible, isn't it?
0:50:28 > 0:50:31Overnight, the fish obviously starts to deteriorate,
0:50:31 > 0:50:34so I'm trying to just get the fish mashed up.
0:50:34 > 0:50:35It'll be a very strong mix
0:50:35 > 0:50:39and what we're trying to achieve is a very strong odour trail,
0:50:39 > 0:50:42like a corridor for the sharks to follow right up to the boat.
0:50:45 > 0:50:46That smell is totally revolting.
0:50:48 > 0:50:52Great white sharks have a highly developed sense of smell.
0:50:52 > 0:50:56With tiny holes in their snout, it's thought they can detect
0:50:56 > 0:50:59minute drops of blood in water from up to three miles away.
0:51:03 > 0:51:06- I'm going in. - That's it. Speed is everything.
0:51:06 > 0:51:09Although they have the reputation for being man-eaters,
0:51:09 > 0:51:12great whites rarely attack humans,
0:51:12 > 0:51:14but Philippe can take no chances
0:51:14 > 0:51:17and uses the cage to keep shark watch underwater.
0:51:17 > 0:51:19Man, it's rough down here!
0:51:19 > 0:51:23If we get a hint of seeing a great white shark in the Med,
0:51:23 > 0:51:26doesn't matter how uncomfortable we are.
0:51:35 > 0:51:37Long day, long night.
0:51:37 > 0:51:39We've just got to keep going
0:51:39 > 0:51:42and we're doing everything we can to keep our chances high.
0:51:42 > 0:51:45The whole team is going to be on watch
0:51:45 > 0:51:49and we're just going to keep at it, all hands, 24 hours.
0:51:52 > 0:51:55The team keeps chumming through the night
0:51:55 > 0:51:58and the oily fish slick attracts a tantalising abundance
0:51:58 > 0:52:01of sea life towards the boat.
0:52:01 > 0:52:05It's just gone midnight and the chum slick is suddenly coming alive.
0:52:05 > 0:52:06Here comes...
0:52:06 > 0:52:10What's that, a flying fish?
0:52:10 > 0:52:12These fish have long fins on their sides
0:52:12 > 0:52:16which they use to fly above the water for around 50 metres
0:52:16 > 0:52:18to escape from predators.
0:52:18 > 0:52:24As well as flying fish, there are needle fish and a pelagic octopus.
0:52:24 > 0:52:27Fantastic. Slick's working, then.
0:52:27 > 0:52:29The conditions are right
0:52:29 > 0:52:33and the smelly chum slick is buzzing with life.
0:52:33 > 0:52:38Great whites often hunt at night, using their sense of smell
0:52:38 > 0:52:42to locate their prey, so Philippe returns to the cage.
0:52:42 > 0:52:44All right!
0:52:44 > 0:52:46It is a little choppy,
0:52:46 > 0:52:50but still good conditions and I'm not giving up hope.
0:52:50 > 0:52:53The last sighting of a great white shark,
0:52:53 > 0:52:55that we know of, in the Mediterranean,
0:52:55 > 0:52:58occurred right around here about a year ago.
0:52:58 > 0:53:02What's even more exciting is that the great white sighted
0:53:02 > 0:53:05was a juvenile - only about five feet long -
0:53:05 > 0:53:10which makes it a critical place for the great white shark.
0:53:12 > 0:53:15So even the slightest sign of great white activity here
0:53:15 > 0:53:18could be significant.
0:53:21 > 0:53:26- We'll see, man. We've got all night, see what happens.- Just keep going.
0:53:26 > 0:53:27Yeah, it's all we can do.
0:53:29 > 0:53:34With only a few hours left of the expedition, Ian is on dawn watch.
0:53:36 > 0:53:39Then, as morning breaks...
0:53:39 > 0:53:42Guys, we've got a chum bag pulled out.
0:53:44 > 0:53:49One of our mesh bags, the red one, has been pulled out.
0:53:49 > 0:53:52- That's great news, right? - It takes a lot to do that.
0:53:52 > 0:53:55- That's good news, that. Something's happening.- Yeah.
0:53:55 > 0:53:58So we have definitely had a shark respond to our chum?
0:53:58 > 0:54:00It certainly wasn't those fish!
0:54:00 > 0:54:03It's happening! Can you believe it?
0:54:05 > 0:54:07Encouraged by the encounter,
0:54:07 > 0:54:10the team tries everything to lure the shark back.
0:54:19 > 0:54:24But as the expedition ends, the bite is the closest they get
0:54:24 > 0:54:27to finding evidence of this endangered creature.
0:54:30 > 0:54:31That's it!
0:54:32 > 0:54:35It's a tantalising end to the trip.
0:54:35 > 0:54:37Down a bit, mate.
0:54:37 > 0:54:41But perhaps not such bad news for the shark.
0:54:41 > 0:54:44Although it's a slightly sort of perverse way of looking at it,
0:54:44 > 0:54:47one side of me is somewhat relieved that
0:54:47 > 0:54:50the animals still remain so cryptic and so distant from us
0:54:50 > 0:54:53that we're finding it, with all of our effort,
0:54:53 > 0:54:55difficult to actually get them to come to us,
0:54:55 > 0:55:00which is a shame for us, but possibly good news for white sharks.
0:55:03 > 0:55:07We've only ever explored maybe 5% of our oceans,
0:55:07 > 0:55:11and in a sense, I think that not finding the great white
0:55:11 > 0:55:13is an extension of that mystery.
0:55:15 > 0:55:17As the team have seen,
0:55:17 > 0:55:21humankind is encroaching more and more on this sea.
0:55:21 > 0:55:25The great white might not be able to avoid us for much longer.
0:55:31 > 0:55:32During this expedition,
0:55:32 > 0:55:36the Mediterranean has revealed some of its many secrets.
0:55:36 > 0:55:40Oh, wow, can you believe this?!
0:55:42 > 0:55:46The team has uncovered proof of this sea's dramatic past
0:55:46 > 0:55:48and explored the long relationship
0:55:48 > 0:55:52humans have had with the Mediterranean.
0:55:52 > 0:55:55The expedition has also shown how humans
0:55:55 > 0:56:00can put untold pressure on a delicate ecosystem.
0:56:00 > 0:56:04Quite a bit of life here, but no large fish.
0:56:04 > 0:56:07I'm not comfortable with always using the word "fragile"
0:56:07 > 0:56:11around the earth because I don't think it's a fragile planet.
0:56:11 > 0:56:13I actually think it's very, very robust,
0:56:13 > 0:56:18but the Mediterranean sea - because it's surrounded by so much input
0:56:18 > 0:56:21and there's so much stock being taken
0:56:21 > 0:56:24and we're asking so much of this small sea -
0:56:24 > 0:56:28that I think anybody that came and experienced what I just have,
0:56:28 > 0:56:33I think it would totally reset people's thinking and attitudes
0:56:33 > 0:56:35towards the Mediterranean sea.
0:56:37 > 0:56:41This sea is many things to many people -
0:56:41 > 0:56:43a holiday destination,
0:56:43 > 0:56:47a historical treasure chest, a food resource for millions.
0:56:49 > 0:56:51It's a rich and diverse environment
0:56:51 > 0:56:56with a precious history and a vital future, both of which need securing.
0:57:06 > 0:57:08Next time,
0:57:08 > 0:57:12the team braves one of the most hostile environments on the planet -
0:57:12 > 0:57:13the Arctic Ocean.
0:57:15 > 0:57:19They dive beneath the vanishing ice cap
0:57:19 > 0:57:22and explore how changes to this frozen sea
0:57:22 > 0:57:26are threatening the ocean's life, and the rest of the planet.
0:57:26 > 0:57:31We are completely dependent on the stuff that keeps the planet cold.
0:57:50 > 0:57:53Subtitles by Red Bee Media Ltd
0:57:53 > 0:57:56E-mail subtitling@bbc.co.uk