Mountains of the Deep Atlantic: The Wildest Ocean on Earth

There's an ocean where giants gather to feast...

..where people battle the planet's roughest seas.

EXPLODING

It stretches nearly 10,000 miles...

from Arctic to Antarctic.

PENGUINS HONK

THEY BARK

From tropical shallows...

..to mysterious depths...

..it's an ocean of extremes.

A engine room for storms 1,000 miles across...

..yet also a sanctuary for the vulnerable.

People and animals brave this unpredictable ocean...

..risking it all for rich rewards.

This is the Atlantic...

..the wildest ocean on Earth.

WAVES CRASH

Travel away from land into the centre of the Atlantic

and you enter a vast, blue desert.

No sea floor, or plants, or coral might grow.

No animals, no sign of life.

Or so it appears.

Blue jack mackerel.

They have shoaled here by their thousands to breed.

But their gathering has attracted attention.

DOLPHIN CLICKS

A group of common dolphins.

Close behind...spotted dolphins.

DOLPHINS CLICK

The two species collaborate to herd the fish into a ball.

There's no escape.

The bait ball is pinned against the surface,

under attack from every direction.

From above...

sheer waters.

The bait ball gets broken into smaller fragments.

Few mackerel will survive.

But the fish consumed,

the predators depart.

This fleeting gathering took place far out in the open ocean

because of something that happens deep beneath the surface.

Our vast geological forces throw up huge undersea mountains

and stir the ocean into life.

60 million years ago

an immense rift tore open the planet's surface.

Magma poured out

pushing America apart from Europe,

opening up the world's youngest ocean...

..the Atlantic.

DEEP RUMBLING

The crack in the earth's crust is still visible today.

This is the Silfra Gap in Iceland -

a strange no-man's land between two continents.

On the left side, America,

and on the right, Europe.

Over millions of years this crack spread,

opening up the Atlantic as it went.

And beneath the new ocean, that colossal upheaval threw up

the world's longest mountain range.

The Mid-Atlantic Ridge runs along the sea floor,

down the centre of the ocean, for 10,000 miles.

This undersea mountain range is vital for life in the ocean.

1,000 miles west of Portugal,

two brave explorers are preparing to drop into the abyss.

OK, let's go on our journey.

This mission is to uncover the secrets of life on

the Mid-Atlantic Ridge.

Husband and wife team Kirsten and Joachim Jakobsen

built this submarine themselves.

They rely on communication with the ship above in order to find

the ridge.

Are you right on top of us?

'We are northwest...

'maybe 300 metres to get to it.'

OK, thank you.

200 metres down is beyond the reach of sunlight.

And beyond 600 metres is a world as little-known

as outer space.

736 metres.

In everywhere you dive, you discover new things,

so a journey into the deep is a journey to another planet.

After nearly an hour, they reach the ocean floor -

over half a mile down and a few hundred metres

from the Mid-Atlantic Ridge.

The sea floor is just a vast, empty plain of mud.

But as the explorers pilot towards the ridge, life begins to appear.

The first foothills of the Mid-Atlantic Ridge.

I think we feel like discoverers, somehow.

We go to locations where no-one has ever been before.

Here at the bottom of the ocean, gardens have sprung to life.

Fields of sea fans, sponges and soft corals.

Over the past 20 years, Kirsten and Joachim

have discovered species that were completely new to science.

The deep-sea wonderland supports a rich food chain.

An angler fish breaks camouflage to ambush passing prey.

A squid dismembers another fish with its sharp beak.

An octopus overwhelms its prey.

Here, there's even enough food for giants.

At five metres long, these sixgill sharks have remained

virtually unchanged for more than 200 million years.

These predators move slowly to conserve energy.

They feed on whale carcasses falling from above.

Nice. Yes!

To protect themselves,

some animals have adopted ingenious defence measures.

These decorator crabs rarely venture far without an umbrella.

This isn't a form of camouflage -

these crabs live their lives in pitch blackness.

Researchers think the crabs choose corals and sponges with stings,

using them as a living shield to repel predators.

So, what has turned these undersea mountains

into such a rich oasis of life?

The answer lies with the nutrient-rich current,

which flows through the deep.

It's travelled thousands of miles across the sea floor

from the Arctic and here, it collides with the ridge.

These nutrients in the current

feed the foundations of a remarkable pyramid of life.

And here in the deep, it's only the start.

Bye-bye, deep sea, until the next time.

The submarine follows the current

as it's deflected up towards the surface.

As they rise, they encounter other creatures of the deep,

sustained by the rich, upwelling current.

Comb jellies can grow to more than a metre across.

Thousands of hairs catch the submarine's light,

beating to propel it through the water.

Next come clouds of krill -

tiny shrimp, the food of giant blue whales.

What's this?

Strange.

Oh, there's a histio.

Yes, histioteuthis. Yes!

Oh, we have to be very careful now.

At the edge of where sunlight can penetrate,

the bizarre strawberry squid.

It has two different-sized eyes for hunting in this unusual world.

The large eye points upwards

to scan for silhouettes in the twilight.

And a smaller one scans for bioluminescent prey

glowing in the depths.

At last, the submarine returns to sunlit water.

The nutrients welling up from below combine with the sunlight

to create an oasis of life in the heart of the Atlantic.

From small fish like blue jack mackerel

to voracious predators like these barracuda...

..many animals journey thousands of miles to feast here

in the peak summer season.

These mobula rays, over three metres across,

have travelled from the coast of Africa.

A blue shark - another wonder of the ocean desert.

And these - sperm whales, the largest toothed animal on earth.

They feed 1,000 metres down

on deep-sea squid and even deep-sea sharks.

The abundant life here supports

a population of hundreds of these whales.

The Mid-Atlantic Ridge has transformed the open ocean

into an oasis for life.

In some parts of the Atlantic,

the volcanic forces that created the ridge are

so powerful that the mountains are driven right up to the surface.

One million years ago, the tip of a volcano broke the surface

just south of the equator to create the island of Ascension.

It is one of the newest and most lonely islands

in the South Atlantic...

..and home to a very strange ecosystem.

The shallow waters around the island are dominated by one animal -

the black triggerfish.

Few competitors have yet made it

across the vast stretches of open ocean.

Triggerfish will eat almost anything.

And they are here in such numbers that little coral or seaweed

can gain a foothold.

Seabird chicks that fall in the water are soon snapped up.

Sick or injured triggerfish don't last long, either.

Above the waves, barren volcanic rocks bake

in more than 30 degrees Celsius under the equatorial sun.

This truly is a desert island.

The diary of a Dutch sailor was found here centuries ago.

He survived just six months in this waterless place,

drinking the blood of sea turtles to survive.

But some castaways have made Ascension their permanent home.

Ascension land crabs, the size of a man's fist,

are the largest native animals on the island.

Their larvae drifted here on ocean currents

and the adults survived by foraging on the lava fields.

To escape the searing equatorial heat,

the crabs live high up,

where it's cooler and there's moisture from the clouds,

but they still have to lay their eggs in seawater.

So, every year, the female crabs face an epic journey to the ocean.

To escape the heat of the day, they travel mostly at night.

Almost all the crabs head for just a few beaches -

perhaps the ones where they first came ashore as youngsters.

For some, that means travelling halfway across the island -

the equivalent of a person walking 100 miles.

They drink from occasional pools of condensation on the rocks.

They don't drink with their mouths -

they absorb water through their rear legs.

Dawn brings an end to their week-long trek.

But after travelling all this way, the females avoid the sea.

Right now, the sea is full of predatory triggerfish.

It's just too risky.

So the crabs gather in caves at the edge of the beach,

sheltered from the sun, and wait for nightfall.

The cave is filled with the gentle sound of sleeping crabs.

The triggerfish are ready to turn in for the night.

They have few predators here, so they sleep out in the open.

But the coasts of Ascension are swept

by powerful swells and currents...

..so they must take precautions.

The spike on the dorsal fin originally evolved

as a defence against predators.

They use it to wedge themselves securely into place.

The triggerfish are sleeping.

It's just before new moon.

Exactly the conditions the crabs have been waiting for.

The new moon brings powerful tides

which will carry their young far out to sea.

At the edge of the surf, a vigorous shake dislodges their eggs.

Swarms of tiny mole crabs emerge from beneath the sand

to feast on the eggs.

But there are so many land crabs

that millions of their progeny will make it to the sea.

They'll be sustained by the nutrients

welling up around the island.

And in a few weeks, some will return to land,

re-enacting the colonisation of this extraordinary island.

Where volcanic forces have created islands closer to continents,

the opportunities for life are far greater.

Just over 200 miles off the coast of Brazil lies Fernando de Noronha.

This steep-sided island rises 4,000 metres from the seafloor

on an offshoot of the Mid-Atlantic Ridge.

Fernando is a young island, like Ascension...

..but there, the similarity ends.

Brazil is so close that many seeds

have blown or floated across to the island.

BIRDSONG

And because no land predators have ever swum over here...

Fernando is also a haven for birds.

Red-footed boobies are just one of the many species that breed here.

Fairy terns are known locally as "little brides".

Black noddies are known as "widow birds".

They build their nests from seaweed.

All these birds breed here because it's safe,

but also because of the rich seas.

The island's steep sides

drive nutrient-rich seafloor currents to the surface.

And the plentiful food

makes the island popular with a remarkable animal.

The twisting leaps of

male spinner dolphins

are a common sight around Fernando.

They hunt squid in the rich offshore waters at night.

And by day, over 2,000 gather to rest in the island's sheltered bays.

The largest group of spinners anywhere in the world.

There are so many dolphins so close to shore

that scientists have been able to study their behaviour...

..revealing the secrets of their complex social lives in detail.

Older male dolphins take turns on guard duty,

keeping a lookout for predators like tiger sharks.

This leaves the rest of the pod

free to socialise with each other in safety.

A young calf plays in the heart of a group...

..while resting adults enjoy each other's company.

It turns out the dolphins

have surprisingly human ways to pass the time.

This is the dolphin equivalent of catch.

Studies have led one scientist

to speculate on one of the big questions about these animals.

Why do they spin?

It looks like a visual display.

But now studies here are focusing on the loud splash

a spinning dolphin makes when it hits the water.

The scientists noticed that the dolphins

spun more often when their boat approached,

and realised that the spinning may be a response to a perceived threat.

Tiger sharks are common here.

The guard male's first defence is to lure the shark away from the group.

But they can also spin.

The loud splashes may be a danger signal to the group.

And perhaps help drive the predator away.

Thanks to its location close to South America,

the volcanic forces that shaped Fernando de Noronha

have created a tropical island paradise.

Further south, volcanic forces have also been at work,

shaping the life of the southern seas.

A wandering albatross patrols the far south of the Atlantic,

perfectly adapted to seek out the ocean's oases.

His huge three-metre wingspan

allows him to spend most of his life on the wing.

He even feeds on the wing, skimming the surface to catch fish and squid.

These cold and storm-tossed seas may look uninviting,

but, in fact, there is a lot of food to be found here...

..if you know where to look.

2,000 metres down, remotely operated submarines

have uncovered a bizarre and unexpected world.

12-metre tall volcanic chimneys

spew superheated sulphurous water into the freezing ocean.

But there is life here.

Huge aggregations of strange white crabs...

..some as large as dinner plates.

Hoff crabs rely on the sulphur in the water to survive,

but they are at constant risk of getting cooked.

These crabs are named in honour of actor David Hasselhoff

because of their lavishly hairy chests.

Bacteria growing in these hairs

feed on the sulphurous chemicals in the water.

In turn, bacteria are food for the crabs.

Males spend their entire lives in the warm water,

competing for top spots and females.

For an egg-carrying female...

life is harder.

Her eggs are easily damaged by the heat and the sulphur -

she must move away into colder water.

Here, cold and unable to feed,

her body itself starts to decay.

If she survives long enough to release her larvae,

they will drift with the currents in search

of another oasis like this one.

Here in the remote south,

the same tectonic forces that support the Hoff crabs in the deep

have thrown up huge island chains.

The South Sandwich Islands

are a chain of volcanoes that rose up five million years ago.

Today, hot sulphurous gases

still pour from the bare and inhospitable terrain.

The island looks bleak,

but there is life here.

-Lots of it.

-SQUAWKING

Three million chinstrap penguins

come to this volcano every year to breed.

It is one of the largest penguin colonies in the world.

And it is just one of hundreds of colonies in the Southern Ocean.

These penguins prosper because of the huge geological upheaval

which transformed the waters of the South Atlantic.

40 million years ago, South America and Antarctica drifted apart,

allowing the world's most powerful ocean current

to encircle the south of our planet.

The Antarctic Circumpolar Current

stirs up nutrients from the seafloor and enriches the southern seas.

A branch of this current curls up

and reaches the waters around the Falkland Islands.

In these shallow seas,

sunlight combines with the current's fertility

to create one of the fastest-growing forests on earth.

Macrocystis kelp fronds

can grow up to 60cm a day.

Huge numbers of animals thrive in this underwater forest.

For many, like these saffron sea cucumbers, the forest is a nursery.

They carry their tiny young

until they are old enough to fend for themselves.

But of all the animals here,

perhaps this little one has the biggest role.

Lobster krill,

closely related to hermit crabs.

They feed on the kelp forests' dead.

These two are squabbling over the remains of a jellyfish.

In late summer, young lobster krill swarm in vast numbers.

A plentiful food supply for many animals.

Gentoo penguins time their breeding season

to coincide with this annual explosion of food.

Bellies full, they swim back to their colonies.

Over 100,000 pairs of gentoos breed in the Falklands every year.

The parents take it in turns to stay ashore and feed the chicks...

..though the chicks will have to catch them first.

Eventually, the parent relents...

..and the chick gets its meal...

..semi-digested lobster krill.

Anyone wanting seconds

has to wait for the next shift of adults to return.

But danger lurks in the waves.

Southern sea lions patrol the shallows.

The penguins make a dash for the beach.

But they're not safe - even on dry land.

Sea lions have forward-facing rear flippers,

which allow them to chase the penguins up the beach.

So perhaps all that running which the penguins did as chicks

was useful training after all.

A lucky escape.

Though with so many penguins heading to and from the ocean...

..the sea lion is sure of a meal sometime soon.

South of the Falklands, the mighty Circumpolar Current

sweeps on around the planet,

bringing life to the South Atlantic.

Commerson's dolphins feed on small fish and shellfish.

Humpback whales feed on huge blooms of krill.

There's plenty of food for fur seals too.

There is life here in abundance.

And nowhere more than in the waters around one very special island...

South Georgia.

100 miles long and about 15 miles wide,

it is the top of a mountain range that sits in the full force

of the Circumpolar Current.

Despite freezing temperatures and brutal storms,

this is a hotspot for life.

The island's steep sides divert nourishing water

from the Circumpolar Current up to the surface.

Sea temperatures here seldom rise above five degrees Celsius,

even in summer,

and cold water is rich in life-giving oxygen.

These fertile seas support nearly 1,500 species.

Many come here to breed.

Penguins...

..seals...

and even a meat-eating duck -

the South Georgia pintail.

Every two years, wandering albatrosses

take a break from life on the wing.

WIND HOWLS

Many come to South Georgia to breed.

Here, there are very few ground predators

to steal their valuable eggs.

After a marathon nine months on the nest,

the chick will make its first clumsy attempt at a life in the air.

Unsurprisingly, humans were quick to cash in

on South Georgia's richness.

Captain Cook discovered the island in 1775

and sent home reports of the abundant wildlife.

Hunters soon followed,

slaughtering fur seals and elephant seals for their skins.

Over the next 50 years, more than a million pelts were taken

and fur seals nearly went extinct here.

Whalers arrived at the start of the 20th century.

Harvests quickly grew, but then the industry collapsed.

In 1965, people finally realised that the hunting had to stop

and the island was left eerily empty.

But exploitation of the seas around the island continued,

with devastating effects on the island's albatrosses.

Industrial-scale fishing began in earnest in the 1960s.

Trawlers hauled in massive catches of rock cod and ice fish.

The industry expanded without management or regulation.

By the 1980s, ships had began longlining,

using hooks baited with squid.

Thousands of albatrosses were killed on the long lines of hooks.

But today...there is hope.

These longliners look the same,

but now there are compulsory measures in place

to reduce albatross deaths.

Heavily weighted fishing lines can be set only under cover of darkness,

so the birds can't see the baited hooks.

And when they're hauling in their lines,

the fishermen put out streamers

to deter the birds from approaching the hooks.

The data that these ships collect is fed directly back

to the scientists that manage the fishery...

..a partnership that is helping arrest the decline

of the wandering albatross.

If the rest of the world's fishing fleets follow suit,

then there is hope for these wonderful birds.

Today, South Georgia is coming back to life.

Whales are returning,

fed by the Circumpolar Current.

And as winter turns to summer, the island is transformed.

The old whaling and sealing bases have been repossessed by nature.

A whaling ship - imperial shags now nest on it.

And below, fur seals play in the wreckage.

Of all the animals that were nearly hunted out of existence,

the Antarctic fur seal has made the most remarkable comeback.

Today, 90% of the world's population come to this island to breed...

..a staggering three million individuals.

Nearly half a million southern elephant seals also come here -

half the world's population.

Here is the greatest mass of marine mammals anywhere on earth.

BIRDSONG

The beaches are packed shoulder-to-shoulder

with half a million nesting penguins.

87 species of bird can be found on South Georgia,

including four different types of albatross.

It's an extraordinary mass of animals

on a lonely island in a cold, storm-tossed ocean.

More than anywhere else in the Atlantic,

South Georgia reveals how mountains rearing up from the seafloor

can transform a lifeless blue desert into an oasis.

All made possible by the vast geological forces

that first gave birth, millions of years ago,

to this great ocean...the Atlantic.

The quest to film the Atlantic's islands and undersea mountains

took our film crews almost from Pole to Pole,

from Iceland in the north

to South Georgia on the edge of the Antarctic.

They were attacked by sea lice,

crawled on by crabs...

Get it off, Dave, please.

They even braved the crushing depths of the abyss.

But their biggest challenge was 8,000 miles south, in the Falklands,

in search of a vital link in the Atlantic food chain -

lobster krill.

The hunt will test cameraman and ex-marine Mike Pitts

to his limits,

fighting extreme conditions to get those crucial shots.

His first challenge is cramming his gear onto the boat.

And, please, come into my cabin.

I'm sleeping on the top bunk and a lot of the camera kit

is actually going on the bottom bunk,

so the boat is full to the gunnels.

But I'm looking forward to it, it's going to be an amazing trip.

The team know there are krill here,

enough to support the countless penguins, fish and other creatures that feed on them,

but finding them turns out to be tricky.

A kelp forest just an hour's sail from Port Stanley -

the perfect place for young krill to hide from predators.

There are plenty of small animals taking shelter amongst the fronds,

but no sign of krill.

The trip is not completely wasted -

a young sea lion comes to check them out.

What was nice was the sea lion coming at the end. What a cracker.

It just threw a pirouette right on the sand.

It looked really magic... At 40 frames!

On the advice of local experts, the team travelled further west.

They find what looks like an ideal site close to a sea lion colony.

The dive starts well.

Then, suddenly...

a threat bursts out of the gloom.

A bull sea lion - weighing a third of a tonne -

defending his territory.

With a head like a grizzly bear,

he could cause serious damage.

He bares his teeth and snorts aggressively.

But luckily for the team, he lets them leave without attacking.

I'm just glad we're all out in one piece.

There was no ifs and buts, it was, "Let's get out of the water,"

because you just got this feeling that the next thing that could happen...

That one of us could have been bitten.

Another unsuccessful dive.

And then events take a turn for the worse...

It may be summer here,

but the weather in the Falklands can still deteriorate quickly.

Antarctica is only a short hop away.

They must wait two days for the storm to pass.

Although it's still choppy, the team don't want to lose any more time.

The sea is so churned up, their visibility is close to zero.

Now desperate to find krill,

the divers spend too long in the freezing water.

I got cold. I got cold on that dive.

Spirits hit an all-time low.

And Mike has fallen ill.

-Diving with a cold can lead to serious ear damage.

-So here we go.

So eyes down, look in.

Excuse me.

Mike has to get his nose clear if he's to carry on diving.

Well, I hope that works. It should do.

HE SIGHS

With time running out, it's clear the team need a new approach.

They have to avoid unnecessary dives in the cold water.

The answer...a small camera on a rope.

Camera's still running.

A fish-eye's view of the world under the boat.

That's a lobster krill. That's a lobster krill!

CHEERING AND APPLAUSE

LAUGHTER

-That's great.

-Brilliant!

-Look. Look, look!

-Oh, yeah.

-This is superb! This is brilliant!

-There you go. Dive, dive, dive!

LAUGHTER

-That is so cool.

-WHOOPING

We're right on the edge - we couldn't have a better location

and we're slightly out of the wind here.

Finally, a result, even better than they dared to hope.

I looked up...and that's when I saw this sight,

a sort of colony of bees that had gone into a swarm.

Seeing that for the first time was quite amazing.

They even come face-to-face with a group

of gentoo penguins, here to feed.

Mission accomplished.

And on their way back to Stanley...

further proof that persistence pays off.

Oh! Dolphin!

LAUGHTER

There's so many of them.

Commerson's dolphins are only found in a few places worldwide.

The perfect way to end a tough but rewarding trip.

Well, we've just come to the end of what has been

a remarkable two and a half weeks'

circumnavigation of the Falkland Islands.

So many things we've shot - we've filmed the lobster krill,

which has been incredible,

but now it's time to say goodbye to the Falklands.

By the skin of their teeth, the Atlantic team

have pulled off another successful trip.

The tropical Atlantic is not quite what it seems.

Life is on a knife edge for animals and people.

What happens when Caribbean heaven

turns to Atlantic hell?