0:00:06 > 0:00:09There's an ocean where giants gather to feast...
0:00:13 > 0:00:16..where people battle the planet's roughest seas.
0:00:17 > 0:00:19EXPLODING
0:00:19 > 0:00:22It stretches nearly 10,000 miles...
0:00:22 > 0:00:24from Arctic to Antarctic.
0:00:24 > 0:00:26PENGUINS HONK
0:00:26 > 0:00:28THEY BARK
0:00:30 > 0:00:31From tropical shallows...
0:00:33 > 0:00:35..to mysterious depths...
0:00:41 > 0:00:43..it's an ocean of extremes.
0:00:46 > 0:00:49A engine room for storms 1,000 miles across...
0:00:51 > 0:00:54..yet also a sanctuary for the vulnerable.
0:00:57 > 0:01:00People and animals brave this unpredictable ocean...
0:01:02 > 0:01:05..risking it all for rich rewards.
0:01:07 > 0:01:09This is the Atlantic...
0:01:10 > 0:01:13..the wildest ocean on Earth.
0:01:13 > 0:01:15WAVES CRASH
0:01:30 > 0:01:33Travel away from land into the centre of the Atlantic
0:01:33 > 0:01:36and you enter a vast, blue desert.
0:01:39 > 0:01:42No sea floor, or plants, or coral might grow.
0:01:42 > 0:01:45No animals, no sign of life.
0:01:47 > 0:01:48Or so it appears.
0:01:55 > 0:01:58Blue jack mackerel.
0:01:58 > 0:02:01They have shoaled here by their thousands to breed.
0:02:03 > 0:02:06But their gathering has attracted attention.
0:02:10 > 0:02:12DOLPHIN CLICKS
0:02:15 > 0:02:17A group of common dolphins.
0:02:22 > 0:02:25Close behind...spotted dolphins.
0:02:25 > 0:02:27DOLPHINS CLICK
0:02:29 > 0:02:33The two species collaborate to herd the fish into a ball.
0:02:36 > 0:02:38There's no escape.
0:02:38 > 0:02:41The bait ball is pinned against the surface,
0:02:41 > 0:02:44under attack from every direction.
0:02:46 > 0:02:48From above...
0:02:48 > 0:02:50sheer waters.
0:03:18 > 0:03:21The bait ball gets broken into smaller fragments.
0:03:24 > 0:03:26Few mackerel will survive.
0:03:38 > 0:03:40But the fish consumed,
0:03:40 > 0:03:41the predators depart.
0:03:43 > 0:03:47This fleeting gathering took place far out in the open ocean
0:03:47 > 0:03:51because of something that happens deep beneath the surface.
0:03:52 > 0:03:57Our vast geological forces throw up huge undersea mountains
0:03:57 > 0:04:00and stir the ocean into life.
0:04:14 > 0:04:1660 million years ago
0:04:16 > 0:04:20an immense rift tore open the planet's surface.
0:04:21 > 0:04:24Magma poured out
0:04:24 > 0:04:28pushing America apart from Europe,
0:04:28 > 0:04:30opening up the world's youngest ocean...
0:04:31 > 0:04:33..the Atlantic.
0:04:33 > 0:04:35DEEP RUMBLING
0:04:41 > 0:04:44The crack in the earth's crust is still visible today.
0:04:47 > 0:04:51This is the Silfra Gap in Iceland -
0:04:51 > 0:04:55a strange no-man's land between two continents.
0:04:55 > 0:04:58On the left side, America,
0:04:58 > 0:05:00and on the right, Europe.
0:05:01 > 0:05:04Over millions of years this crack spread,
0:05:04 > 0:05:07opening up the Atlantic as it went.
0:05:10 > 0:05:14And beneath the new ocean, that colossal upheaval threw up
0:05:14 > 0:05:16the world's longest mountain range.
0:05:24 > 0:05:27The Mid-Atlantic Ridge runs along the sea floor,
0:05:27 > 0:05:30down the centre of the ocean, for 10,000 miles.
0:05:32 > 0:05:36This undersea mountain range is vital for life in the ocean.
0:05:37 > 0:05:401,000 miles west of Portugal,
0:05:40 > 0:05:44two brave explorers are preparing to drop into the abyss.
0:05:44 > 0:05:46OK, let's go on our journey.
0:05:50 > 0:05:53This mission is to uncover the secrets of life on
0:05:53 > 0:05:54the Mid-Atlantic Ridge.
0:05:58 > 0:06:01Husband and wife team Kirsten and Joachim Jakobsen
0:06:01 > 0:06:04built this submarine themselves.
0:06:14 > 0:06:17They rely on communication with the ship above in order to find
0:06:17 > 0:06:19the ridge.
0:06:21 > 0:06:23Are you right on top of us?
0:06:24 > 0:06:26'We are northwest...
0:06:26 > 0:06:30'maybe 300 metres to get to it.'
0:06:31 > 0:06:33OK, thank you.
0:06:36 > 0:06:39200 metres down is beyond the reach of sunlight.
0:06:46 > 0:06:50And beyond 600 metres is a world as little-known
0:06:50 > 0:06:52as outer space.
0:06:56 > 0:06:59736 metres.
0:07:01 > 0:07:04In everywhere you dive, you discover new things,
0:07:04 > 0:07:09so a journey into the deep is a journey to another planet.
0:07:13 > 0:07:17After nearly an hour, they reach the ocean floor -
0:07:17 > 0:07:20over half a mile down and a few hundred metres
0:07:20 > 0:07:22from the Mid-Atlantic Ridge.
0:07:31 > 0:07:35The sea floor is just a vast, empty plain of mud.
0:07:39 > 0:07:44But as the explorers pilot towards the ridge, life begins to appear.
0:07:59 > 0:08:02The first foothills of the Mid-Atlantic Ridge.
0:08:09 > 0:08:12I think we feel like discoverers, somehow.
0:08:12 > 0:08:16We go to locations where no-one has ever been before.
0:08:17 > 0:08:21Here at the bottom of the ocean, gardens have sprung to life.
0:08:26 > 0:08:31Fields of sea fans, sponges and soft corals.
0:08:35 > 0:08:37Over the past 20 years, Kirsten and Joachim
0:08:37 > 0:08:41have discovered species that were completely new to science.
0:08:47 > 0:08:50The deep-sea wonderland supports a rich food chain.
0:08:59 > 0:09:03An angler fish breaks camouflage to ambush passing prey.
0:09:06 > 0:09:09A squid dismembers another fish with its sharp beak.
0:09:14 > 0:09:16An octopus overwhelms its prey.
0:09:19 > 0:09:23Here, there's even enough food for giants.
0:09:26 > 0:09:30At five metres long, these sixgill sharks have remained
0:09:30 > 0:09:34virtually unchanged for more than 200 million years.
0:09:36 > 0:09:39These predators move slowly to conserve energy.
0:09:39 > 0:09:42They feed on whale carcasses falling from above.
0:09:45 > 0:09:47Nice. Yes!
0:09:58 > 0:09:59To protect themselves,
0:09:59 > 0:10:03some animals have adopted ingenious defence measures.
0:10:05 > 0:10:09These decorator crabs rarely venture far without an umbrella.
0:10:11 > 0:10:13This isn't a form of camouflage -
0:10:13 > 0:10:17these crabs live their lives in pitch blackness.
0:10:21 > 0:10:25Researchers think the crabs choose corals and sponges with stings,
0:10:25 > 0:10:28using them as a living shield to repel predators.
0:10:33 > 0:10:36So, what has turned these undersea mountains
0:10:36 > 0:10:38into such a rich oasis of life?
0:10:43 > 0:10:46The answer lies with the nutrient-rich current,
0:10:46 > 0:10:47which flows through the deep.
0:10:51 > 0:10:54It's travelled thousands of miles across the sea floor
0:10:54 > 0:10:58from the Arctic and here, it collides with the ridge.
0:11:02 > 0:11:04These nutrients in the current
0:11:04 > 0:11:08feed the foundations of a remarkable pyramid of life.
0:11:13 > 0:11:17And here in the deep, it's only the start.
0:11:19 > 0:11:23Bye-bye, deep sea, until the next time.
0:11:24 > 0:11:26The submarine follows the current
0:11:26 > 0:11:29as it's deflected up towards the surface.
0:11:32 > 0:11:36As they rise, they encounter other creatures of the deep,
0:11:36 > 0:11:38sustained by the rich, upwelling current.
0:11:46 > 0:11:50Comb jellies can grow to more than a metre across.
0:11:52 > 0:11:55Thousands of hairs catch the submarine's light,
0:11:55 > 0:11:57beating to propel it through the water.
0:12:00 > 0:12:02Next come clouds of krill -
0:12:02 > 0:12:06tiny shrimp, the food of giant blue whales.
0:12:11 > 0:12:12What's this?
0:12:15 > 0:12:16Strange.
0:12:16 > 0:12:18Oh, there's a histio.
0:12:18 > 0:12:21Yes, histioteuthis. Yes!
0:12:21 > 0:12:23Oh, we have to be very careful now.
0:12:25 > 0:12:28At the edge of where sunlight can penetrate,
0:12:28 > 0:12:30the bizarre strawberry squid.
0:12:31 > 0:12:35It has two different-sized eyes for hunting in this unusual world.
0:12:39 > 0:12:41The large eye points upwards
0:12:41 > 0:12:44to scan for silhouettes in the twilight.
0:12:47 > 0:12:50And a smaller one scans for bioluminescent prey
0:12:50 > 0:12:51glowing in the depths.
0:12:57 > 0:13:01At last, the submarine returns to sunlit water.
0:13:22 > 0:13:25The nutrients welling up from below combine with the sunlight
0:13:25 > 0:13:28to create an oasis of life in the heart of the Atlantic.
0:13:34 > 0:13:37From small fish like blue jack mackerel
0:13:37 > 0:13:41to voracious predators like these barracuda...
0:13:45 > 0:13:49..many animals journey thousands of miles to feast here
0:13:49 > 0:13:50in the peak summer season.
0:13:51 > 0:13:55These mobula rays, over three metres across,
0:13:55 > 0:13:57have travelled from the coast of Africa.
0:14:01 > 0:14:05A blue shark - another wonder of the ocean desert.
0:14:17 > 0:14:21And these - sperm whales, the largest toothed animal on earth.
0:14:24 > 0:14:26They feed 1,000 metres down
0:14:26 > 0:14:30on deep-sea squid and even deep-sea sharks.
0:14:34 > 0:14:35The abundant life here supports
0:14:35 > 0:14:38a population of hundreds of these whales.
0:14:51 > 0:14:55The Mid-Atlantic Ridge has transformed the open ocean
0:14:55 > 0:14:56into an oasis for life.
0:15:02 > 0:15:04In some parts of the Atlantic,
0:15:04 > 0:15:06the volcanic forces that created the ridge are
0:15:06 > 0:15:10so powerful that the mountains are driven right up to the surface.
0:15:12 > 0:15:16One million years ago, the tip of a volcano broke the surface
0:15:16 > 0:15:19just south of the equator to create the island of Ascension.
0:15:22 > 0:15:24It is one of the newest and most lonely islands
0:15:24 > 0:15:26in the South Atlantic...
0:15:28 > 0:15:31..and home to a very strange ecosystem.
0:15:36 > 0:15:41The shallow waters around the island are dominated by one animal -
0:15:41 > 0:15:44the black triggerfish.
0:15:50 > 0:15:52Few competitors have yet made it
0:15:52 > 0:15:55across the vast stretches of open ocean.
0:16:04 > 0:16:08Triggerfish will eat almost anything.
0:16:10 > 0:16:13And they are here in such numbers that little coral or seaweed
0:16:13 > 0:16:15can gain a foothold.
0:16:25 > 0:16:30Seabird chicks that fall in the water are soon snapped up.
0:16:35 > 0:16:39Sick or injured triggerfish don't last long, either.
0:16:49 > 0:16:52Above the waves, barren volcanic rocks bake
0:16:52 > 0:16:56in more than 30 degrees Celsius under the equatorial sun.
0:16:58 > 0:17:01This truly is a desert island.
0:17:02 > 0:17:06The diary of a Dutch sailor was found here centuries ago.
0:17:06 > 0:17:10He survived just six months in this waterless place,
0:17:10 > 0:17:13drinking the blood of sea turtles to survive.
0:17:15 > 0:17:18But some castaways have made Ascension their permanent home.
0:17:26 > 0:17:30Ascension land crabs, the size of a man's fist,
0:17:30 > 0:17:33are the largest native animals on the island.
0:17:39 > 0:17:41Their larvae drifted here on ocean currents
0:17:41 > 0:17:44and the adults survived by foraging on the lava fields.
0:17:53 > 0:17:56To escape the searing equatorial heat,
0:17:56 > 0:17:57the crabs live high up,
0:17:57 > 0:18:00where it's cooler and there's moisture from the clouds,
0:18:00 > 0:18:03but they still have to lay their eggs in seawater.
0:18:09 > 0:18:14So, every year, the female crabs face an epic journey to the ocean.
0:18:19 > 0:18:23To escape the heat of the day, they travel mostly at night.
0:18:31 > 0:18:34Almost all the crabs head for just a few beaches -
0:18:34 > 0:18:38perhaps the ones where they first came ashore as youngsters.
0:18:40 > 0:18:44For some, that means travelling halfway across the island -
0:18:44 > 0:18:47the equivalent of a person walking 100 miles.
0:18:53 > 0:18:57They drink from occasional pools of condensation on the rocks.
0:18:57 > 0:18:59They don't drink with their mouths -
0:18:59 > 0:19:01they absorb water through their rear legs.
0:19:09 > 0:19:12Dawn brings an end to their week-long trek.
0:19:18 > 0:19:22But after travelling all this way, the females avoid the sea.
0:19:24 > 0:19:26Right now, the sea is full of predatory triggerfish.
0:19:28 > 0:19:29It's just too risky.
0:19:35 > 0:19:38So the crabs gather in caves at the edge of the beach,
0:19:38 > 0:19:41sheltered from the sun, and wait for nightfall.
0:19:52 > 0:19:56The cave is filled with the gentle sound of sleeping crabs.
0:20:23 > 0:20:26The triggerfish are ready to turn in for the night.
0:20:28 > 0:20:32They have few predators here, so they sleep out in the open.
0:20:34 > 0:20:37But the coasts of Ascension are swept
0:20:37 > 0:20:39by powerful swells and currents...
0:20:41 > 0:20:42..so they must take precautions.
0:20:49 > 0:20:52The spike on the dorsal fin originally evolved
0:20:52 > 0:20:55as a defence against predators.
0:20:55 > 0:20:58They use it to wedge themselves securely into place.
0:21:05 > 0:21:07The triggerfish are sleeping.
0:21:09 > 0:21:10It's just before new moon.
0:21:12 > 0:21:15Exactly the conditions the crabs have been waiting for.
0:21:20 > 0:21:22The new moon brings powerful tides
0:21:22 > 0:21:25which will carry their young far out to sea.
0:21:36 > 0:21:41At the edge of the surf, a vigorous shake dislodges their eggs.
0:21:46 > 0:21:49Swarms of tiny mole crabs emerge from beneath the sand
0:21:49 > 0:21:51to feast on the eggs.
0:21:56 > 0:21:57But there are so many land crabs
0:21:57 > 0:22:00that millions of their progeny will make it to the sea.
0:22:08 > 0:22:10They'll be sustained by the nutrients
0:22:10 > 0:22:11welling up around the island.
0:22:14 > 0:22:18And in a few weeks, some will return to land,
0:22:18 > 0:22:21re-enacting the colonisation of this extraordinary island.
0:22:31 > 0:22:34Where volcanic forces have created islands closer to continents,
0:22:34 > 0:22:37the opportunities for life are far greater.
0:22:40 > 0:22:45Just over 200 miles off the coast of Brazil lies Fernando de Noronha.
0:22:48 > 0:22:53This steep-sided island rises 4,000 metres from the seafloor
0:22:53 > 0:22:56on an offshoot of the Mid-Atlantic Ridge.
0:23:02 > 0:23:05Fernando is a young island, like Ascension...
0:23:06 > 0:23:10..but there, the similarity ends.
0:23:12 > 0:23:14Brazil is so close that many seeds
0:23:14 > 0:23:17have blown or floated across to the island.
0:23:17 > 0:23:19BIRDSONG
0:23:32 > 0:23:36And because no land predators have ever swum over here...
0:23:36 > 0:23:40Fernando is also a haven for birds.
0:23:41 > 0:23:45Red-footed boobies are just one of the many species that breed here.
0:23:48 > 0:23:52Fairy terns are known locally as "little brides".
0:23:59 > 0:24:01Black noddies are known as "widow birds".
0:24:04 > 0:24:06They build their nests from seaweed.
0:24:12 > 0:24:14All these birds breed here because it's safe,
0:24:14 > 0:24:17but also because of the rich seas.
0:24:23 > 0:24:25The island's steep sides
0:24:25 > 0:24:28drive nutrient-rich seafloor currents to the surface.
0:24:33 > 0:24:34And the plentiful food
0:24:34 > 0:24:38makes the island popular with a remarkable animal.
0:24:45 > 0:24:46The twisting leaps of
0:24:46 > 0:24:48male spinner dolphins
0:24:48 > 0:24:50are a common sight around Fernando.
0:24:55 > 0:24:58They hunt squid in the rich offshore waters at night.
0:25:01 > 0:25:06And by day, over 2,000 gather to rest in the island's sheltered bays.
0:25:09 > 0:25:13The largest group of spinners anywhere in the world.
0:25:18 > 0:25:21There are so many dolphins so close to shore
0:25:21 > 0:25:24that scientists have been able to study their behaviour...
0:25:26 > 0:25:30..revealing the secrets of their complex social lives in detail.
0:25:34 > 0:25:37Older male dolphins take turns on guard duty,
0:25:37 > 0:25:40keeping a lookout for predators like tiger sharks.
0:25:43 > 0:25:45This leaves the rest of the pod
0:25:45 > 0:25:48free to socialise with each other in safety.
0:25:54 > 0:25:56A young calf plays in the heart of a group...
0:25:59 > 0:26:02..while resting adults enjoy each other's company.
0:26:05 > 0:26:06It turns out the dolphins
0:26:06 > 0:26:09have surprisingly human ways to pass the time.
0:26:14 > 0:26:17This is the dolphin equivalent of catch.
0:26:35 > 0:26:37Studies have led one scientist
0:26:37 > 0:26:41to speculate on one of the big questions about these animals.
0:26:47 > 0:26:49Why do they spin?
0:26:52 > 0:26:54It looks like a visual display.
0:27:01 > 0:27:04But now studies here are focusing on the loud splash
0:27:04 > 0:27:07a spinning dolphin makes when it hits the water.
0:27:19 > 0:27:21The scientists noticed that the dolphins
0:27:21 > 0:27:24spun more often when their boat approached,
0:27:24 > 0:27:29and realised that the spinning may be a response to a perceived threat.
0:27:36 > 0:27:38Tiger sharks are common here.
0:27:46 > 0:27:50The guard male's first defence is to lure the shark away from the group.
0:27:57 > 0:27:59But they can also spin.
0:28:01 > 0:28:05The loud splashes may be a danger signal to the group.
0:28:08 > 0:28:10And perhaps help drive the predator away.
0:28:16 > 0:28:20Thanks to its location close to South America,
0:28:20 > 0:28:24the volcanic forces that shaped Fernando de Noronha
0:28:24 > 0:28:27have created a tropical island paradise.
0:28:35 > 0:28:39Further south, volcanic forces have also been at work,
0:28:39 > 0:28:42shaping the life of the southern seas.
0:28:46 > 0:28:51A wandering albatross patrols the far south of the Atlantic,
0:28:51 > 0:28:55perfectly adapted to seek out the ocean's oases.
0:28:55 > 0:28:58His huge three-metre wingspan
0:28:58 > 0:29:00allows him to spend most of his life on the wing.
0:29:03 > 0:29:07He even feeds on the wing, skimming the surface to catch fish and squid.
0:29:09 > 0:29:13These cold and storm-tossed seas may look uninviting,
0:29:13 > 0:29:16but, in fact, there is a lot of food to be found here...
0:29:17 > 0:29:19..if you know where to look.
0:29:29 > 0:29:332,000 metres down, remotely operated submarines
0:29:33 > 0:29:37have uncovered a bizarre and unexpected world.
0:29:42 > 0:29:4512-metre tall volcanic chimneys
0:29:45 > 0:29:49spew superheated sulphurous water into the freezing ocean.
0:29:53 > 0:29:55But there is life here.
0:29:58 > 0:30:01Huge aggregations of strange white crabs...
0:30:03 > 0:30:05..some as large as dinner plates.
0:30:11 > 0:30:16Hoff crabs rely on the sulphur in the water to survive,
0:30:16 > 0:30:19but they are at constant risk of getting cooked.
0:30:23 > 0:30:27These crabs are named in honour of actor David Hasselhoff
0:30:27 > 0:30:30because of their lavishly hairy chests.
0:30:30 > 0:30:33Bacteria growing in these hairs
0:30:33 > 0:30:36feed on the sulphurous chemicals in the water.
0:30:36 > 0:30:40In turn, bacteria are food for the crabs.
0:30:43 > 0:30:46Males spend their entire lives in the warm water,
0:30:46 > 0:30:49competing for top spots and females.
0:30:51 > 0:30:54For an egg-carrying female...
0:30:54 > 0:30:56life is harder.
0:30:56 > 0:30:59Her eggs are easily damaged by the heat and the sulphur -
0:30:59 > 0:31:02she must move away into colder water.
0:31:03 > 0:31:06Here, cold and unable to feed,
0:31:06 > 0:31:09her body itself starts to decay.
0:31:13 > 0:31:16If she survives long enough to release her larvae,
0:31:16 > 0:31:18they will drift with the currents in search
0:31:18 > 0:31:20of another oasis like this one.
0:31:32 > 0:31:34Here in the remote south,
0:31:34 > 0:31:38the same tectonic forces that support the Hoff crabs in the deep
0:31:38 > 0:31:41have thrown up huge island chains.
0:31:46 > 0:31:48The South Sandwich Islands
0:31:48 > 0:31:52are a chain of volcanoes that rose up five million years ago.
0:31:56 > 0:31:58Today, hot sulphurous gases
0:31:58 > 0:32:02still pour from the bare and inhospitable terrain.
0:32:06 > 0:32:08The island looks bleak,
0:32:08 > 0:32:11but there is life here.
0:32:11 > 0:32:13- Lots of it. - SQUAWKING
0:32:18 > 0:32:21Three million chinstrap penguins
0:32:21 > 0:32:24come to this volcano every year to breed.
0:32:27 > 0:32:31It is one of the largest penguin colonies in the world.
0:32:39 > 0:32:44And it is just one of hundreds of colonies in the Southern Ocean.
0:32:59 > 0:33:03These penguins prosper because of the huge geological upheaval
0:33:03 > 0:33:06which transformed the waters of the South Atlantic.
0:33:11 > 0:33:1640 million years ago, South America and Antarctica drifted apart,
0:33:16 > 0:33:19allowing the world's most powerful ocean current
0:33:19 > 0:33:22to encircle the south of our planet.
0:33:24 > 0:33:26The Antarctic Circumpolar Current
0:33:26 > 0:33:32stirs up nutrients from the seafloor and enriches the southern seas.
0:33:32 > 0:33:34A branch of this current curls up
0:33:34 > 0:33:37and reaches the waters around the Falkland Islands.
0:33:45 > 0:33:47In these shallow seas,
0:33:47 > 0:33:49sunlight combines with the current's fertility
0:33:49 > 0:33:53to create one of the fastest-growing forests on earth.
0:34:01 > 0:34:03Macrocystis kelp fronds
0:34:03 > 0:34:07can grow up to 60cm a day.
0:34:15 > 0:34:19Huge numbers of animals thrive in this underwater forest.
0:34:31 > 0:34:37For many, like these saffron sea cucumbers, the forest is a nursery.
0:34:39 > 0:34:40They carry their tiny young
0:34:40 > 0:34:43until they are old enough to fend for themselves.
0:34:48 > 0:34:51But of all the animals here,
0:34:51 > 0:34:54perhaps this little one has the biggest role.
0:35:02 > 0:35:04Lobster krill,
0:35:04 > 0:35:07closely related to hermit crabs.
0:35:09 > 0:35:12They feed on the kelp forests' dead.
0:35:16 > 0:35:20These two are squabbling over the remains of a jellyfish.
0:35:29 > 0:35:35In late summer, young lobster krill swarm in vast numbers.
0:35:37 > 0:35:40A plentiful food supply for many animals.
0:35:56 > 0:35:58Gentoo penguins time their breeding season
0:35:58 > 0:36:02to coincide with this annual explosion of food.
0:36:17 > 0:36:21Bellies full, they swim back to their colonies.
0:36:26 > 0:36:31Over 100,000 pairs of gentoos breed in the Falklands every year.
0:36:33 > 0:36:37The parents take it in turns to stay ashore and feed the chicks...
0:36:38 > 0:36:41..though the chicks will have to catch them first.
0:37:15 > 0:37:17Eventually, the parent relents...
0:37:19 > 0:37:21..and the chick gets its meal...
0:37:25 > 0:37:28..semi-digested lobster krill.
0:37:30 > 0:37:32Anyone wanting seconds
0:37:32 > 0:37:35has to wait for the next shift of adults to return.
0:37:36 > 0:37:39But danger lurks in the waves.
0:37:54 > 0:37:57Southern sea lions patrol the shallows.
0:38:01 > 0:38:04The penguins make a dash for the beach.
0:38:09 > 0:38:12But they're not safe - even on dry land.
0:38:33 > 0:38:36Sea lions have forward-facing rear flippers,
0:38:36 > 0:38:39which allow them to chase the penguins up the beach.
0:38:44 > 0:38:47So perhaps all that running which the penguins did as chicks
0:38:47 > 0:38:49was useful training after all.
0:38:58 > 0:39:00A lucky escape.
0:39:04 > 0:39:07Though with so many penguins heading to and from the ocean...
0:39:09 > 0:39:12..the sea lion is sure of a meal sometime soon.
0:39:20 > 0:39:24South of the Falklands, the mighty Circumpolar Current
0:39:24 > 0:39:26sweeps on around the planet,
0:39:26 > 0:39:29bringing life to the South Atlantic.
0:39:39 > 0:39:43Commerson's dolphins feed on small fish and shellfish.
0:39:46 > 0:39:49Humpback whales feed on huge blooms of krill.
0:39:52 > 0:39:54There's plenty of food for fur seals too.
0:39:57 > 0:40:00There is life here in abundance.
0:40:00 > 0:40:04And nowhere more than in the waters around one very special island...
0:40:06 > 0:40:09South Georgia.
0:40:09 > 0:40:12100 miles long and about 15 miles wide,
0:40:12 > 0:40:16it is the top of a mountain range that sits in the full force
0:40:16 > 0:40:18of the Circumpolar Current.
0:40:21 > 0:40:24Despite freezing temperatures and brutal storms,
0:40:24 > 0:40:27this is a hotspot for life.
0:40:29 > 0:40:33The island's steep sides divert nourishing water
0:40:33 > 0:40:36from the Circumpolar Current up to the surface.
0:40:49 > 0:40:53Sea temperatures here seldom rise above five degrees Celsius,
0:40:53 > 0:40:55even in summer,
0:40:55 > 0:40:58and cold water is rich in life-giving oxygen.
0:41:06 > 0:41:10These fertile seas support nearly 1,500 species.
0:41:12 > 0:41:15Many come here to breed.
0:41:17 > 0:41:18Penguins...
0:41:19 > 0:41:22..seals...
0:41:22 > 0:41:24and even a meat-eating duck -
0:41:24 > 0:41:26the South Georgia pintail.
0:41:29 > 0:41:32Every two years, wandering albatrosses
0:41:32 > 0:41:34take a break from life on the wing.
0:41:34 > 0:41:36WIND HOWLS
0:41:37 > 0:41:40Many come to South Georgia to breed.
0:41:43 > 0:41:45Here, there are very few ground predators
0:41:45 > 0:41:47to steal their valuable eggs.
0:41:50 > 0:41:53After a marathon nine months on the nest,
0:41:53 > 0:41:58the chick will make its first clumsy attempt at a life in the air.
0:42:01 > 0:42:05Unsurprisingly, humans were quick to cash in
0:42:05 > 0:42:07on South Georgia's richness.
0:42:09 > 0:42:13Captain Cook discovered the island in 1775
0:42:13 > 0:42:16and sent home reports of the abundant wildlife.
0:42:19 > 0:42:21Hunters soon followed,
0:42:21 > 0:42:26slaughtering fur seals and elephant seals for their skins.
0:42:27 > 0:42:32Over the next 50 years, more than a million pelts were taken
0:42:32 > 0:42:34and fur seals nearly went extinct here.
0:42:38 > 0:42:41Whalers arrived at the start of the 20th century.
0:42:45 > 0:42:49Harvests quickly grew, but then the industry collapsed.
0:42:57 > 0:43:01In 1965, people finally realised that the hunting had to stop
0:43:01 > 0:43:04and the island was left eerily empty.
0:43:08 > 0:43:12But exploitation of the seas around the island continued,
0:43:12 > 0:43:15with devastating effects on the island's albatrosses.
0:43:17 > 0:43:21Industrial-scale fishing began in earnest in the 1960s.
0:43:23 > 0:43:27Trawlers hauled in massive catches of rock cod and ice fish.
0:43:33 > 0:43:37The industry expanded without management or regulation.
0:43:40 > 0:43:43By the 1980s, ships had began longlining,
0:43:43 > 0:43:46using hooks baited with squid.
0:43:51 > 0:43:54Thousands of albatrosses were killed on the long lines of hooks.
0:44:10 > 0:44:12But today...there is hope.
0:44:15 > 0:44:18These longliners look the same,
0:44:18 > 0:44:21but now there are compulsory measures in place
0:44:21 > 0:44:24to reduce albatross deaths.
0:44:24 > 0:44:28Heavily weighted fishing lines can be set only under cover of darkness,
0:44:28 > 0:44:31so the birds can't see the baited hooks.
0:44:34 > 0:44:36And when they're hauling in their lines,
0:44:36 > 0:44:38the fishermen put out streamers
0:44:38 > 0:44:40to deter the birds from approaching the hooks.
0:44:43 > 0:44:46The data that these ships collect is fed directly back
0:44:46 > 0:44:48to the scientists that manage the fishery...
0:44:51 > 0:44:54..a partnership that is helping arrest the decline
0:44:54 > 0:44:56of the wandering albatross.
0:45:00 > 0:45:04If the rest of the world's fishing fleets follow suit,
0:45:04 > 0:45:06then there is hope for these wonderful birds.
0:45:14 > 0:45:18Today, South Georgia is coming back to life.
0:45:21 > 0:45:23Whales are returning,
0:45:23 > 0:45:25fed by the Circumpolar Current.
0:45:46 > 0:45:50And as winter turns to summer, the island is transformed.
0:45:54 > 0:45:58The old whaling and sealing bases have been repossessed by nature.
0:46:13 > 0:46:17A whaling ship - imperial shags now nest on it.
0:46:23 > 0:46:26And below, fur seals play in the wreckage.
0:46:30 > 0:46:34Of all the animals that were nearly hunted out of existence,
0:46:34 > 0:46:37the Antarctic fur seal has made the most remarkable comeback.
0:46:40 > 0:46:45Today, 90% of the world's population come to this island to breed...
0:46:48 > 0:46:52..a staggering three million individuals.
0:46:57 > 0:47:02Nearly half a million southern elephant seals also come here -
0:47:02 > 0:47:04half the world's population.
0:47:18 > 0:47:23Here is the greatest mass of marine mammals anywhere on earth.
0:47:23 > 0:47:24BIRDSONG
0:47:27 > 0:47:30The beaches are packed shoulder-to-shoulder
0:47:30 > 0:47:33with half a million nesting penguins.
0:47:37 > 0:47:4187 species of bird can be found on South Georgia,
0:47:41 > 0:47:45including four different types of albatross.
0:47:51 > 0:47:54It's an extraordinary mass of animals
0:47:54 > 0:47:59on a lonely island in a cold, storm-tossed ocean.
0:48:06 > 0:48:08More than anywhere else in the Atlantic,
0:48:08 > 0:48:13South Georgia reveals how mountains rearing up from the seafloor
0:48:13 > 0:48:18can transform a lifeless blue desert into an oasis.
0:48:20 > 0:48:23All made possible by the vast geological forces
0:48:23 > 0:48:26that first gave birth, millions of years ago,
0:48:26 > 0:48:30to this great ocean...the Atlantic.
0:48:44 > 0:48:47The quest to film the Atlantic's islands and undersea mountains
0:48:47 > 0:48:51took our film crews almost from Pole to Pole,
0:48:51 > 0:48:53from Iceland in the north
0:48:53 > 0:48:55to South Georgia on the edge of the Antarctic.
0:48:58 > 0:49:01They were attacked by sea lice,
0:49:01 > 0:49:03crawled on by crabs...
0:49:03 > 0:49:05Get it off, Dave, please.
0:49:05 > 0:49:09They even braved the crushing depths of the abyss.
0:49:11 > 0:49:15But their biggest challenge was 8,000 miles south, in the Falklands,
0:49:15 > 0:49:19in search of a vital link in the Atlantic food chain -
0:49:19 > 0:49:21lobster krill.
0:49:28 > 0:49:32The hunt will test cameraman and ex-marine Mike Pitts
0:49:32 > 0:49:33to his limits,
0:49:33 > 0:49:37fighting extreme conditions to get those crucial shots.
0:49:41 > 0:49:46His first challenge is cramming his gear onto the boat.
0:49:46 > 0:49:48And, please, come into my cabin.
0:49:48 > 0:49:51I'm sleeping on the top bunk and a lot of the camera kit
0:49:51 > 0:49:53is actually going on the bottom bunk,
0:49:53 > 0:49:56so the boat is full to the gunnels.
0:49:56 > 0:49:59But I'm looking forward to it, it's going to be an amazing trip.
0:50:01 > 0:50:03The team know there are krill here,
0:50:03 > 0:50:08enough to support the countless penguins, fish and other creatures that feed on them,
0:50:08 > 0:50:11but finding them turns out to be tricky.
0:50:20 > 0:50:24A kelp forest just an hour's sail from Port Stanley -
0:50:24 > 0:50:28the perfect place for young krill to hide from predators.
0:50:44 > 0:50:47There are plenty of small animals taking shelter amongst the fronds,
0:50:47 > 0:50:49but no sign of krill.
0:51:04 > 0:51:07The trip is not completely wasted -
0:51:07 > 0:51:09a young sea lion comes to check them out.
0:51:14 > 0:51:18What was nice was the sea lion coming at the end. What a cracker.
0:51:18 > 0:51:22It just threw a pirouette right on the sand.
0:51:27 > 0:51:30It looked really magic... At 40 frames!
0:51:32 > 0:51:36On the advice of local experts, the team travelled further west.
0:51:44 > 0:51:48They find what looks like an ideal site close to a sea lion colony.
0:52:02 > 0:52:04The dive starts well.
0:52:07 > 0:52:09Then, suddenly...
0:52:09 > 0:52:12a threat bursts out of the gloom.
0:52:13 > 0:52:16A bull sea lion - weighing a third of a tonne -
0:52:16 > 0:52:19defending his territory.
0:52:26 > 0:52:29With a head like a grizzly bear,
0:52:29 > 0:52:31he could cause serious damage.
0:52:31 > 0:52:34He bares his teeth and snorts aggressively.
0:52:39 > 0:52:44But luckily for the team, he lets them leave without attacking.
0:52:46 > 0:52:48I'm just glad we're all out in one piece.
0:52:48 > 0:52:52There was no ifs and buts, it was, "Let's get out of the water,"
0:52:52 > 0:52:55because you just got this feeling that the next thing that could happen...
0:52:55 > 0:52:57That one of us could have been bitten.
0:52:59 > 0:53:01Another unsuccessful dive.
0:53:04 > 0:53:07And then events take a turn for the worse...
0:53:15 > 0:53:17It may be summer here,
0:53:17 > 0:53:21but the weather in the Falklands can still deteriorate quickly.
0:53:21 > 0:53:23Antarctica is only a short hop away.
0:53:25 > 0:53:28They must wait two days for the storm to pass.
0:53:32 > 0:53:36Although it's still choppy, the team don't want to lose any more time.
0:53:45 > 0:53:48The sea is so churned up, their visibility is close to zero.
0:53:48 > 0:53:50Now desperate to find krill,
0:53:50 > 0:53:53the divers spend too long in the freezing water.
0:54:07 > 0:54:11I got cold. I got cold on that dive.
0:54:13 > 0:54:15Spirits hit an all-time low.
0:54:15 > 0:54:17And Mike has fallen ill.
0:54:23 > 0:54:27- Diving with a cold can lead to serious ear damage.- So here we go.
0:54:27 > 0:54:29So eyes down, look in.
0:54:29 > 0:54:32Excuse me.
0:54:32 > 0:54:36Mike has to get his nose clear if he's to carry on diving.
0:54:39 > 0:54:42Well, I hope that works. It should do.
0:54:42 > 0:54:44HE SIGHS
0:54:48 > 0:54:52With time running out, it's clear the team need a new approach.
0:54:54 > 0:54:58They have to avoid unnecessary dives in the cold water.
0:55:00 > 0:55:03The answer...a small camera on a rope.
0:55:04 > 0:55:06Camera's still running.
0:55:08 > 0:55:11A fish-eye's view of the world under the boat.
0:55:32 > 0:55:35That's a lobster krill. That's a lobster krill!
0:55:35 > 0:55:37CHEERING AND APPLAUSE
0:55:37 > 0:55:39LAUGHTER
0:55:39 > 0:55:40- That's great.- Brilliant!
0:55:40 > 0:55:43- Look. Look, look!- Oh, yeah.
0:55:43 > 0:55:46- This is superb! This is brilliant! - There you go. Dive, dive, dive!
0:55:46 > 0:55:48LAUGHTER
0:55:48 > 0:55:50- That is so cool. - WHOOPING
0:55:50 > 0:55:52We're right on the edge - we couldn't have a better location
0:55:52 > 0:55:54and we're slightly out of the wind here.
0:55:56 > 0:56:00Finally, a result, even better than they dared to hope.
0:56:14 > 0:56:19I looked up...and that's when I saw this sight,
0:56:19 > 0:56:23a sort of colony of bees that had gone into a swarm.
0:56:23 > 0:56:26Seeing that for the first time was quite amazing.
0:56:26 > 0:56:28They even come face-to-face with a group
0:56:28 > 0:56:31of gentoo penguins, here to feed.
0:56:45 > 0:56:47Mission accomplished.
0:56:50 > 0:56:52And on their way back to Stanley...
0:56:52 > 0:56:55further proof that persistence pays off.
0:56:55 > 0:56:56Oh! Dolphin!
0:56:56 > 0:56:58LAUGHTER
0:56:58 > 0:57:00There's so many of them.
0:57:00 > 0:57:03Commerson's dolphins are only found in a few places worldwide.
0:57:03 > 0:57:07The perfect way to end a tough but rewarding trip.
0:57:09 > 0:57:11Well, we've just come to the end of what has been
0:57:11 > 0:57:13a remarkable two and a half weeks'
0:57:13 > 0:57:15circumnavigation of the Falkland Islands.
0:57:15 > 0:57:18So many things we've shot - we've filmed the lobster krill,
0:57:18 > 0:57:20which has been incredible,
0:57:20 > 0:57:23but now it's time to say goodbye to the Falklands.
0:57:27 > 0:57:30By the skin of their teeth, the Atlantic team
0:57:30 > 0:57:32have pulled off another successful trip.
0:57:49 > 0:57:54The tropical Atlantic is not quite what it seems.
0:57:54 > 0:57:57Life is on a knife edge for animals and people.
0:57:59 > 0:58:01What happens when Caribbean heaven
0:58:01 > 0:58:03turns to Atlantic hell?