Beneath the oceans that cover our planet,
there's an extraordinary world that we humans can barely see.
But the life story of one ocean creature can light up the abyss.
This film will take you on an impossible journey,
following a sperm whale into the eternal darkness of the deep.
We've seen our whale as a youngster learning to master this alien world.
Now he's grown up and he's ready to travel further
and dive deeper than any other creature on Earth,
facing new dangers in an ocean that man is changing.
Welcome to the ultimate ocean odyssey.
The largest predator on our planet lies stranded on a beach in New Zealand.
If this sperm whale is not returned to the ocean soon, he'll die here.
Most of his life has been spent over two kilometres beneath the waves,
so a stranding like this provides us with a unique insight
into a world about which we know so little.
These scars are evidence of creatures we've never seen alive.
And blood tests reveal something extraordinary.
They show that although this bull was found here in the Pacific,
he comes from a family of Atlantic whales.
At some point in his life, he must have undertaken a rare crossing
from one ocean into another.
Ajourney that started at the southern tip of the Americas,
where the largest ocean current in the world funnels through a gap just 800 kilometres wide,
creating the fiercest stretch of ocean on the planet, Drake Passage.
Deep below, the sea floor is littered with wrecks.
A graveyard for generations of sailors.
Using the most powerful sonar in the animal kingdom,
sperm whales penetrate the darkness of the deep.
Down here, wrecks provide a foothold for life,
a home for sea fans and sponges, wreckfish and squid.
An opportunity for a hungry whale.
The bull is in his prime.
Only males develop teeth.
It takes over 30 years for them to reach full size, and each one can weigh over a kilo.
But they aren't for hunting.
He's now ready to use his teeth to challenge other bulls
and fight for the right to mate.
Most whales of his age head north towards the equator to look for females,
but the ocean is about to lure him into a detour to the west.
Six hundred metres down,
he's entering a mysterious layer of water that's filled with the sounds of a distant ocean.
He's inside a phenomenon called the SOFAR channel,
picking up calls of whales from hundreds of kilometres away.
Here, sound becomes trapped,
bouncing between warm water at the surface and the cold, dense water of the deep.
It can be transmitted across entire oceans.
What he's tuning into is a group of over 40 young bulls preparing to dive.
By 1960, sperm whales are being hunted at a rate of 30,000 a year.
A gathering like this is becoming an increasingly rare sight.
The social clicks of Pacific whales are different from their Atlantic neighbours,
not so much a new language as a strange accent.
But the gang seem to be open to all comers,
even this stranger from the east.
There are advantages to such a large group.
The hunting clicks of one whale can signal the discovery of a shoal of fish
that they can all cash in on.
From now on, the Pacific will be his home.
And he's not the only mammal starting a new adventure in this great ocean.
It's January the 3rd, 1960.
And far to the west, two men are attempting a voyage into the unknown.
Aboard the Trieste, they're heading for the deepest point on Earth,
the bottom of the Marianna Trench.
The main section of the submarine is a fuel-filled buoyancy tank.
The men are suspended in a tiny steel sphere below it,
and they have a long way to go.
Throw a rock into the water here,
and it will take over an hour before it hits the bottom, 11 kilometres down.
The Pacific is the deepest ocean of them all.
Towards the western fringes of this giant ocean,
the movement of the Earth's crust drives the seabed under the continent of Asia,
creating a vast depression in the Earth's mantle,
an ocean valley of gigantic proportions.
If it is to succeed, the Trieste's steel capsule will have to withstand pressures
of 1,000 times greater than those on the surface.
It's getting cold.
At 800 metres, the temperature is only three degrees above freezing.
Travelling at three kilometres an hour, it will take them fours hours to reach the bottom.
The sperm whale falls into the abyss at a steady speed of five kilometres an hour,
and a four-inch layer of blubber protects him from the cold.
At 1,800 metres, a tonne of pressure pushes down on every inch of the craft.
Matt, it's leaking again.
It should stop soon.
God, how does anything survive out here?
The whale's lungs shrink to half their size under a collapsible rib cage.
A protective mucus stops them from sticking together permanently.
At two and a half kilometres down, the craft has reached the limit
of even the largest of whales.
From this moment on, the sperm whale will lose its record
as the deepest mammal on the planet.
For the men... -What was that?
...it's still another eight kilometres to the bottom.
-Have we touched the bottom? -No, we are still falling.
Any flaw in the system could cause implosion.
And halfway into the dive,
an exit window develops a hairline crack.
The aquanauts have undertaken this extreme dive not even knowing what awaits them at the bottom.
They cannot slow their descent in a hurry.
If the floor is a thick soup of marine snow, they know the craft could be engulfed.
Fifteen. Slowing up.
I can see the bottom. Brace yourself.
Wonderful!
No one had ever imagined that there could be life
at such crushing pressures.
It's the beginning of a new appreciation of our ocean depths.
But to understand the true scale and variety of life in the deep,
you need to know where to look.
And the most inhospitable environment on the planet hides its secret well.
This tiny craft sits at the bottom of a trench
that could swallow Mount Everest with a few kilometres to spare.
They have a long journey home.
And like all great explorers, they leave their mark for future generations.
But no one will attempt to reach these depths again.
It's as if the hell of the deep is too difficult
and the heavens are easier to explore.
...override off. Engine arm off. 4 1 3 is in.
We copy you down, Eagle.
By 1969, we knew more about the lifeless surface of the moon...
The Eagle has landed.
...than we did about the deep oceans of our own planet.
You got a bunch of guys about to turn blue.
We're breathing again. Thanks a lot.
But from space, the enduring image is that ours is a blue planet.
99% of the habitable area on Earth is in the deep.
In the years following the Trieste dive, our exploration of the deep may have stalled,
but our exploitation of the oceans accelerated.
By the 1970s, the world's fishing fleets had found new ways of harvesting the oceans.
This long-liner can drag 20,000 hooks to depths of over two kilometres.
Mankind's hunting techniques are directly encroaching on the sperm whale territory.
But they don't have the biggest brains on the planet for nothing.
The Atlantic whale is learning a new trick from its Pacific cousins.
They've discovered that the sound of the boats' motors
signals the start of a giant sushi trolley bringing fresh fish up from the depths.
But they're not the only whales who've learnt to race to this dinner bell.
In any ocean, killer whales and sperm whales are old adversaries.
The Atlantic bull still bears the scars from when he was attacked as a calf.
Now he's three times their size.
The sheer persistence of the orcas usually pays off.
And anyway, these bulls are on a mission,
searching for females in the warmer waters to the north.
The route they follow takes them along a giant ridge
that stretches 8,000 kilometres along the length of the ocean,
the East Pacific Rise.
Here, the movement of the Earth's crust is pulling the ocean floor apart.
Similar to the Mid-Atlantic Ridge, it allows magma to seep out of the Earth's core,
causing volcanic mountains to rise from the seabed.
But there's one big difference here.
These plates are moving apart at speeds five times faster than those of the Atlantic.
And when this ridge blows, all hell is let loose.
It starts with explosions of pillow lava, created as molten rock meets icy water.
And all along the fracture, dormant volcanoes are brought to life,
some three times the size of Mount St Helens.
Magma found in the Pacific can be so fluid
that it spreads at speeds of over 30 kilometres an hour,
creating giant lava lakes.
And on a bad day,
the ridge can split the ocean floor
in what scientists call the curtain of fire.
On the surface, there'll be no sign of the storm raging 2,000 metres below.
For the whales, the ridge provides a habitat for a chain of deep-sea life,
a feeding corridor taking the north towards the mating grounds of the Galápagos.
Around these islands, there's a steaming gateway
that creates one of the most exotic landscapes of the deep.
It's a place that's attracting the attention of man.
A submarine named Alvin is following strange temperature readings coming from below.
At 1,600 metres down, the mystery of the readings is solved.
Vents of superheated water bursting from the seabed.
Then something far more unexpected,
a discovery that will change our view of life on Earth.
Huge tube worms, new species of crab and shrimp,
a new kind of life form.
This unique world is not based upon what falls from above.
Instead, it's fuelled by the energy of the steaming vents themselves.
Until this moment, scientists have thought that sunlight
was the sole energy source driving all life on Earth.
Here is evidence that life can find another way.
Alvin's spotlights have illuminated the scientific discovery of the decade,
but the research team have no way of appreciating the scale of the landscape that surrounds them.
This discovery of the deep means that all life on Earth
could have started here in the abyss.
The edges of this volatile world provide the sperm whale
with an opportunity to catch an eelpout or two.
As dissolved minerals solidify, the dark chimneys rise from the seabed,
growing to over 70 metres in just a few years.
But the earthquakes which roll through this deep-sea world
mean that they are all ultimately doomed.
Eight million years of ceaseless volcanic activity
has culminated in the volcanoes of the Galápagos Islands.
And just like the Azores in the Atlantic,
they provide the perfect habitat for the sperm whales to breed.
The bulls respond to the clicks of the female groups.
But this fearsome noise spells trouble.
At 55 years old, the skin of this male is almost white with battle scars.
His sonic clangs are strong enough to stun a human diver.
The sound alone is enough to settle most confrontations,
and it sends the two younger bulls fleeing.
But the Atlantic whale is ready for a fight.
Locking jaws keeps the dangerous teeth at bay.
The younger whale is smaller, but he's more agile.
The gash across the nose is enough to persuade the old bull
that he's met his match.
The spoils of this battle are a chance to pass on his genes in a whole new ocean.
He will stay with this group of females for up to a month.
It's the start of a new phase in his life, roaming the Pacific alone,
visiting female groups time and again to sire more and more offspring.
No, not here! Go round there. Hurry up!
By the end of his life,
this whale had travelled far enough to circumnavigate the globe 40 times.
And as man started to change the oceans of the world,
it caused a struggle for survival that pushed this whale into Antarctica,
a place only the oldest and largest of bulls can go.
The whale is 80 years old, a veteran of the deep ocean.
As he approaches the warm waters off Hawaii,
he's tracking down the breeding groups that live around here.
When he was born, sperm whales numbered over a million animals.
Whaling reduced them to under a quarter that size.
Now these resourceful predators are starting to recover,
but it still takes some skill to find the females.
Ahead of him is the tallest mountain on Earth.
Measured from its base, five kilometres below the sea,
the main island of Hawaii is 1,000 metres taller than Everest.
As usual, he's constantly wary and alert to the presence of other rival bulls.
A monster approaches.
Pulsing his sonar at the beast, a crystal clear image returns.
The nuclear submarine is the ultimate deep-sea machine.
It cruises at depths of 1,000 metres, and can stay down here for up to a year.
The sub is running silent.
She's being hunted and any noise will give her away.
On the surface, a destroyer is trying to find her, listening for the slightest noise.
The submarine is built for silence.
She may displace 9,000 tonnes, but she emits as little noise as a hairdryer.
The whale has found himself in the middle of a war game.
The submarine cannot see her surroundings,
but a supercomputer charts every metre of her journey,
the calculations plotted out on a virtual map of the seabed.
The sub eases up to a giant cliff. She's hiding.
The tracking ship is using whale technology to see into the deep.
Sending pulses of sound and listening to the echo.
The giant sea cliff is confusing the image.
To the whale, these sonar pings are akin to searing flashes of light.
He's leaving just in time.
The flotilla has a secret weapon.
The fin-shaped array emits a low frequency wave louder than a jet fighter taking off.
The sonic shock bounces back details hidden to ordinary sonar.
Target acquired. 303 300.
For the sub, the game is up.
For the whale, a pressure wave is travelling towards him
at 5,000 kilometres per hour.
Reeling, the whale surfaces.
His senses slowly return,
but the water seems alive with noise.
Travelling at 25 knots, a container ship hull is a deadly hammer.
The propeller screws are at the rear.
The bow is silent.
A deep rumble permeates the ocean,
but it's hard for a whale to work out where it's coming from.
For some species of whales, ship strikes are the biggest killer.
In a panic, he's had no time to prepare his body for the dive.
Short of oxygen, he has to return to the surface quicker than he would like.
As he rises, bubbles of gas in his bones expand like tiny mines,
eating away at his spine.
Even a sperm whale can get the bends.
Forced dives like this can inflict irreversible damage on his ageing body.
At any one time, 30,000 giant ships
are crisscrossing the surface of the world's oceans,
making them more and more crowded.
And as this old whale is about to find out,
man is increasingly invading his deep-water world, too.
Off the coast of Mexico, water flowing off the continent of America
etches a canyon to depths of over two kilometres.
The runoff from the land makes a fertile deep-sea landscape
that's a magnet for life, a beacon for diving whales.
It's taken the bull just eight days to get here,
but the females are unresponsive.
Far from falling over him, they're diving away from him.
Down below, the feeding grounds are strangely quiet.
Man has got here first.
A bottom trawler is devastating the once thriving feeding grounds.
The females are starving.
Bottom trawling is the new slash-and-burn technique of the oceans' farmers.
The majority of fish are now caught this way.
A single net can be big enough to contain three jumbo jets.
The technique destroys a marine habitat about which we know next to nothing.
And each year, an area twice the size of America is scraped bare.
For this giant, it's time to attempt the one thing he hasn't done,
to head to a place untouched by humans
where only the biggest and strongest of males are able to go
and where the food is out of this world.
The contents of a whale's stomach
are still one of the best insights into deep-ocean life.
This regurgitated squid was probably hunted two kilometres below the surface.
Just get this out for you.
And a claw embedded in his skin is from one of the great monsters of the deep.
How long do you think he's got?
A creature even larger than a giant squid,
a beast that only the biggest bulls will take on.
In the last year of his life, the whale heads south
towards one of the most extreme of all ocean environments.
On the way, a milky soup announces the presence of the great building blocks of ocean life.
A plankton bloom is made up of tiny sea creatures and microscopic plants.
During the day, the tiny animals move en masse to the relative safety of the deep,
but down there, jellyfish are waiting.
It's a slow-motion feeding frenzy.
Phytoplankton like this remain near the surface.
They're plants and they're doing what all plants do,
using the energy from the sun to process dissolved carbon dioxide.
The carbon is locked away in their bodies and oxygen released.
Each one absorbs a microscopic amount of carbon,
but the vastness of the oceans multiplies the effect.
They have more influence on our atmosphere than all the forests on the Earth put together.
And when these creatures die, they carry the carbon down to the abyss with them.
Over millions of years, as their bodies sink into the seabed,
the carbon is trapped in the deep, slowly turning into oil.
Anchored by cables to the ocean floor,
this deep-sea oil rig is the tallest man-made structure on Earth.
It's an artificial shelter where life gathers in huge shoals.
A chance for an opportunist predator to stock up on fish.
But today, it's not the fish that catch his eye.
Controlled from the surface,
a remote-operated vehicle is used to run structural checks on the rig.
These cameras can provide tantalising glimpses of life in the gloom.
Today, this sub will record an extraordinary contact.
One of the first images of a sperm whale in the deep.
Of all the strange creations the bull has encountered in the deep,
this apparently benign structure is having the most far-reaching effect on his world.
By burning oil, we are releasing the carbon extracted by the plankton
back into the atmosphere.
There is now more carbon dioxide in our air
than at any time in the last 20 million years.
The effects of a global rise in temperature are felt most acutely
in the Southern Ocean around Antarctica.
Two-thirds of all the world's fresh water is locked in the ice here.
This ice shelf protects one of the few regions of the oceans untouched by humans.
But this is the most extreme of all the deep-sea environments.
Only specialists can live here.
The toothfish survive the cold with antifreeze in its blood.
And high levels of oxygen in the water allow these fish to grow
to over two metres in length.
This deep-sea world is fed by boom-and-bust blooms of plankton.
It's a feast-and-famine regime that encourages the growth of giants.
And here in the depths of the Antarctic,
there's a creature which has remained undiscovered
until recently.
Once, the giant squid was believed to be the biggest of its kind,
so scientists had to come up with a new name for this monster.
They called it colossal squid.
And it's not just larger than its giant cousin.
It's a more active predator, too.
Its tentacles are armed with rotating hooks,
each capable of slicing a two-inch gash deep into whale blubber.
This is the beast of sailors' legends.
The body alone can be five metres long.
Inside is the most ferocious beak in the animal kingdom.
But there is one creature even bigger.
The female.
She can grow to 15 metres in length.
And she's a formidable lover.
The old bull has arrived at the farthest reaches of any sperm whale's range.
Once again, he's tapping into a deep-water niche no other predators can reach.
At the edge of the ice shelf, he starts to hunt.
Usually, surface ice would keep him from approaching the edge of the shelf,
but the melting icecap has created a honeycomb of submarine caverns.
A crystal maze.
He's not designed to navigate through this kind of environment.
It's the first time in his life he's had a roof over his head,
blocking his access to air.
He needs oxygen and fast.
Sperm whales instinctively shy away from the shallows.
They're deep-water hunters.
Their sonar has evolved to hunt the giant spaces of the deep.
The whale's body has been honed by the abyss.
His huge streamlined bulk is designed to cope with marathon dives to extreme pressures.
It takes 10 minutes for him to take in enough oxygen for a deep dive.
The blood in his veins transports the precious gas around his body.
His muscles turn black
as they store enough oxygen to stay under for up to 90 minutes.
It's time to dive deep into the world of giants.
In the eternal darkness of the deep,
the whale's sonar locks on to targets 500 metres away.
The squid's massive eye is designed to pick up the faintest shadow above.
He knows something is out there.
But now the squid's hooks are showing their ferocious power.
A slash to the eye and the squid is free.
But not for long.
Now the squid is wrapped around his head.
The only chance for the whale is to get a grip of its body.
The battle between the two biggest predators on Earth has been won.
For the victor, it marks the final chapter in an epic ocean odyssey.
In his 80 years, he's travelled from the depths of the Grand Banks
to the deep-sea cliffs of the Azores.
He's made over half a million deep dives,
hunting with giants along the volcanic ridge that stretches from Greenland to the Falklands.
He's rounded Cape Horn and survived the fiery Pacific.
From the tallest mountains to the deepest canyons on the planet,
he's taken on the greatest monsters of the abyss.
His life has been about conquering a world we can barely enter.
But these victories have not been without cost.
Every environment has left its mark.
And where does this ocean odyssey end?
At the threshold of our surface world.
For the first time, he can feel his own weight,
but his bulk is crushing the life out of him.
The attempts to return him to the deep are well-intentioned but doomed to failure.
Every odyssey must end somewhere.
Even the greatest on the planet.
His life may be over, but his influence has been spread far across the oceans.
An animal of his age will have sired over 60 offspring.
80 years ago, when the great journey started, we knew next to nothing about the deep.
Now we know enough to see that we are changing the oceans
and that the influence of the abyss extends well beyond the deep.
What we cannot know is the kind of ocean
that the bull's offspring will be swimming in a generation from now.
But the whale's world
may be about to get just a little bit bigger.