It looks like an otherworldly landscape.
But it's of this world, and it's not land.
This eerie realm lies underwater,
beneath the Arctic ice cap.
The ghostly calm here belies the raging storms above.
In the long polar winter,
the sun brings little light and even less heat.
Rarely does the temperature get higher
than 60 degrees below zero.
But despite the crippling cold, there is life,
even here at the ends of the Earth.
Desolate, unforgiving, uninhabitable.
But for many scientists,
the poles are places of fragile beauty.
The polar regions are the most magical places
on this planet.
There's no doubt about it.
It's the most delicate shades of white
and any colour that you want to infuse with that white.
There's greys and blues and pinks and oranges and purples.
But it's always so delicately brushed by the light,
by the sun's rays, depending on the angle of the sun.
It's an incredible range of colour but all very subtle.
It's absolutely beautiful.
Whether they live in or out of the water,
animals that populate the poles face their greatest challenge
in the brutal and pitiless winter.
A veteran of many Arctic winters,
wildlife cameraman Doug Allan waits for the moments
that make it worthwhile.
The Arctic can be desperately horrible.
There's no doubt.
In the middle of winter, when it's dark,
it's cold, -40 centigrade, wind blowing 20 knots,
it is absolutely miserable.
And you wonder why you're there.
But then the polar bear pops its head out,
and everything is fine.
The Arctic in the north is a frozen ocean
surrounded by continents.
In winter, the sea freezes,
creating land bridges that allow predators to hunt on the ice.
They need this food to survive.
In early March, the sea is still covered with ice.
But there are patches of open water that never freeze.
They're called polynyas,
and they're created by currents and winds
that prevent the water from freezing over.
Walruses often winter in polynyas.
Here they have access to air and to the sea,
where they go for food and shelter.
But other animals are there unwillingly,
caught in the freezing seawater.
This young bow head whale was trapped in the ice
since the previous fall.
This poor young whale was just breathing the whole time.
There's no food for it because it was winter,
so there wouldn't be much plankton.
It was up and down, just breathing for the whole winter.
This tiny hole is the only place it can get air
for miles around.
The whale is surviving on fat reserves,
which are running dangerously low.
It's a difficult scene to witness.
As a film-maker,
you should let nature take its course.
We couldn't save the whale.
It was 20 miles away,
so it had to break up before it was gonna be released.
It's a very, very difficult and usually a personal choice.
These beluga whales were also trapped unexpectedly.
They are painfully thin.
And many are horribly scarred.
But their injuries weren't caused by the ice.
They were caused by polar bears,
the largest land predators on Earth.
Normally they prey on much smaller animals.
But a polar bear is nothing if not opportunistic.
A whale would be a welcome feast,
and the trapped belugas are within its reach.
The belugas are aware of the danger lurking on the ice.
They stay underwater as long as possible,
but that's only about 20 minutes.
The nearest open water is 20 miles away from here,
and that's too far.
It will be another two months before the ice melts.
Of course, landing a 14-foot-long whale
that weighs over a ton is no small feat,
even if it's trapped and weakened by starvation.
A beluga is worth the wait.
The weather is getting warmer.
So the longer the bear waits, the larger the hole becomes,
making it more difficult to catch a trapped whale.
These belugas have weathered repeated attacks
in the last six months.
Some less successfully than others.
At last, the bear's patience is rewarded.
The catch is a banquet, and not just for the bear.
Arctic foxes and gulls routinely scavenge meals from bear kills.
In fact, they depend on them to survive the winter.
The remaining belugas still have a long wait
before they're paroled from this frozen prison.
And the giants of the ice
never stop looking for their next meal.
Polar bears are at the top of the Arctic food chain.
They influence the behaviour
of every other animal in the Arctic, especially seals.
Arctic seals have one big problem.
And that is that polar bears can walk out on the sea ice
and hunt them.
So there are two areas on which they can have their pups.
One on the pack ice,
which moves around and is a dangerous habitat in itself
because of the shifting pack and crushing ice.
And the other is on the fast ice.
Now, in any of those situations, if there's a polar bear around,
you want to get your seal pup weaned and independent
as fast as you can.
Harp seal pups are born and weaned
on unstable pack ice.
The white colour of their coats
helps to camouflage them against the snow.
Harp seals have a short but intense nursing period.
The milk the pups drink is 45% fat,
more than 10 times the fat in cow's milk.
And they nurse for just 12 days before being left on their own.
The harp seal's mottled cousins are called hooded seals.
The rather impressive male nasal display
warns others to keep their own noses out of his business.
And it's also very appealing to the opposite sex.
Hooded seal pups nurse on milk that's 60% fat
and for only four days,
the shortest period of any mammal.
Getting a protective layer of blubber
quickly allows them to get in the water
and away from predators sooner.
Ringed seals are the smallest
and most abundant seals in the Arctic Ocean.
Their size allows them to hide their pups
in cosy dens beneath the snow.
But if any predator can sniff them out, it's the polar bear.
And ringed seals are the mainstay of their diet.
The bears can detect seal pups hidden in the snow
from more than a mile away.
In spring, females hunt, accompanied by their new cubs.
A nursing mother needs a steady supply of meat and blubber
to keep her milk flowing.
Without it, her cub will die.
When she finds a den,
the bear pounces on the snow with all her weight
to try and break through.
Our job really is to be a dispassionate observer.
I always think that my actions shouldn't influence
the outcome of a predation event one way or the other.
After all, the polar bear is as entitled to his food
and his survival as the seal is to its survival.
And I think, when I watch these things,
I'm just lost in admiration for the polar bear.
But at the same time,
if that seal is fast enough to escape and avoid the polar bear,
then good luck to him.
To confuse the bear,
the ringed seal uses a number of dens.
A bear usually has to break into several
before finding the prize she seeks.
This mother has struck Arctic gold.
When you're actually watching a bear hunt,
it's hard to say, but you do want the bear to get the seal.
You can't see the seal. It's buried.
So your emotions aren't with the seal.
Your emotions are with this female bear
that's got this tiny cub behind it.
You want that cub to survive. You want it to grow up.
So of course you want the bear to get the seal.
This time, the pup escapes
through a hole in its den that leads to the sea.
Just one attack in 20 succeeds.
But if the polar bear doesn't capture prey soon,
she won't have enough milk for her cub.
So she can't afford to rest.
As the Arctic spring turns into summer,
the sun's heat begins to melt and break up the ice.
The cracks between fragments are called leads.
They're corridors to the open water
for the air-breathing animals,
many of which were trapped over the winter.
Belugas follow the leads to their favourite feeding grounds
in search of fish.
Males can dive to more than 1,500 feet.
With smaller lungs, females and young go to about 900 feet.
In late June and July, narwhals return.
The females, who usually lack tusks,
come first, with their new calves.
The males follow later.
Among the Arctic whales, bow heads are by far the biggest,
measuring up to 60 feet long and weighing nearly 100 tons.
Its fluke is 25 feet from tip to tip.
Scientists often hear these leviathans before they see them.
The first thing you know that there's a bow head in the area
is the 'pshhh!' as the bow head breathes.
They are very, very sensitive whales,
because they've been so massively hunted in the past.
There are very few left, and they are very sensitive.
So ideally, we have got in the water with them, swum with them,
give them some sense of scale, but it's incredibly difficult.
Even to get a shot of them underwater is difficult,
when they're feeding, especially.
The little footage we do get of the bow heads feeding
is incredibly rare.
Whales are undoubtedly awe-inspiring.
They're really magnificent animals.
Until you see a whale for real,
you really have no idea how big they are.
And I must admit that even seeing them from a boat
or from the edge of the ice
often doesn't do justice to their real size.
To do that, you have to slip into the water
and see them coming past like a train, like a locomotive.
Bow heads have the largest mouths
of any animal on Earth.
Its tongue alone weighs a ton.
It eats with baleen,
strips of 12-foot-long overlapping plates
that hang from its upper jaw.
Imagine this great, cavernous thing.
It's about the size of a small garage.
And what the bow head does is swim through the water
with its mouth open,
just engulfing masses of water with food in it.
And then it closes its mouth.
And rather as if you were kind of squeezing air
through your teeth, it squeezes water out through its baleen.
It closes its mouth, its tongue comes up,
pushes out all the water... it comes out like this.
And then all the krill and the cope pods...
cope pods mostly in the Arctic... are on the inside of the baleen.
Then the tongue squeezes them all back down its throat.
That's how baleen works.
Though they dine on tiny morsels,
they make up for it in volume.
A single bow head eats about two tons of food a day.
The smaller, playful belugas
seem to be the most gregarious Arctic whales.
They gather in the thousands
in a few of the large Arctic estuaries
in a kind of beluga family reunion.
The youngest, just weeks old,
swim on their mother's back to make breathing a little easier.
As the tide moves in, the belugas move up the estuary,
venturing into very shallow water.
This is the time of year when they moult,
shedding their old scarred and parasite-ridden skin.
The belugas will stay and mingle here for days or even weeks.
When they come together to moult and they're in that warm water,
moulting and rubbing themselves on the pebbles,
they're social and very chatty, beluga whales...
chitchat, chitchat all the time.
When they're finished moulting,
the belugas will head back out to sea to feed.
They've got to lay on stores of fat
before summer gives way to autumn.
Thin sheets of ice pile up in the shifting currents,
and the leads that led to open water close again like a fist.
By late November,
the Arctic Ocean is once more locked in ice.
And for the creatures eking out a living here,
the struggle to survive the merciless winter begins again.
With winter descending on the Arctic,
Antarctica is welcoming its spring.
Although to call it that may be misleading.
Antarctica is by far
the coldest, windiest place on Earth.
It's covered in a layer of ice more than a mile thick.
Antarctica is considerably colder than the Arctic.
In fact, the coldest temperature ever recorded on Earth,
129 degrees below zero, was logged on this barren continent.
Where the Arctic in the north
is a frozen sea surrounded by continents,
Antarctica in the south
is a continent surrounded by freezing seas.
No land predators can cross that expanse of water.
In fact, there are no four-legged creatures at all.
That makes Antarctica an appealing place
for emperor penguins to live.
When the sea freezes over,
Antarctica effectively doubles in size.
The ice around its shores extends outwards
for hundreds of miles.
The emperors are among the very few animals
that can survive here.
Over the 40 years he's been studying Antarctic animals,
Dr. Gerald Kooyman has developed a deep respect for them.
Emperor penguins, there's not much in common
with most other animals.
They are the only ones that I'm aware of
that face the winter head-on.
And that's, I think, true in the Arctic or the Antarctic.
The males stay in the colony all winter
to incubate the eggs left in their care by the females,
who are off feeding in the ocean.
They go months without eating,
huddling together to take on the savage storms.
They take turns warming up inside the circle
before returning to the outside to brave the wind.
Only cooperation keeps them alive.
The Weddell seal uses a different strategy to survive...
it stays in the water.
The average winter low in Antarctica
is 100 degrees below zero.
But the water never gets colder than 28 degrees above.
What they excel in is diving under ice
and foraging under ice.
And they're probably, of the Antarctic seals,
the deepest divers.
So they have a large range they can cover.
And so they turn it into more of a three-dimensional habitat,
where they can live under fast ice.
If they stay back in fast ice, they really have no predators.
But they still need to breathe.
So they keep their breathing holes open
by scraping the ice with their front teeth,
allowing them to live under the ice all winter.
But all that rubbing wears down their teeth,
compromising their ability to hunt and eat.
It's one reason Weddell seals tend to die young.
Weddells aren't alone under the ice.
Krill also stay here all winter long.
They feed by scraping algae from the underside of the ice.
In spring, air bubbles trapped in the frozen ice are released.
The krill feed on the microscopic algae
that grow around these bubbles.
They shovel the algae into their mouths with their beating legs.
As the ice melts,
krill flock together to feast on the floating algae
now swelling in number around them.
Further north, beyond the sea ice,
chinstrap penguins have been wintering in the open ocean.
In spring, they head back to solid ground to breed.
They use the occasional iceberg as a rest stop,
although negotiating the on-ramp can be treacherous.
Finally, at the rocky shore, they have to pick the right wave
and carefully time their leap.
But reaching dry land is only the first step
of a very long journey.
Most will have to walk for miles to find a suitable nesting site.
This is the largest penguin colony on Earth.
It's on Zavodovski Island,
about 1,000 miles from the Antarctic Peninsula.
About 2 million chinstraps breed here every year.
The island is a populous spot for a very good reason...
it's an active volcano.
Although its last known eruption was in the 19th century,
heat continues to escape from the crater
and the many fumaroles,
helping to keep ice and snow off the slopes.
This allows the chinstraps to start breeding earlier
than their cousins further south.
Unlike the emperor penguins,
who have to keep their eggs off the ice,
chinstraps can lay their eggs
right on the bare, heated ground.
This may explain
why so many brave the wild ride it takes to get here.
In the Antarctic spring,
the blanket of sea ice around the continent breaks up.
Icebergs that were locked in the frozen sea ice
are again set adrift.
Seasonal visitors begin to arrive.
Minke whales are the most common whale in the southern ocean.
In summer, they visit the calm waters here to feed.
Like many others, they come for the krill,
the staple of the Antarctic diet.
And it's here in astonishing numbers.
A single swarm can consist of billions of individual krill
and can stretch out for miles.
Virtually every animal in the Antarctic,
regardless of size, depends on krill.
The humpback is another whale who drops by for a bite to eat.
Well, many bites, really.
A humpback can swallow hundreds of thousands of krill
in a single colossal gulp.
Their winter breeding grounds are thousands of miles away,
in the tropics.
But they too are drawn here by the promise of a hearty meal.
We were in the Antarctic, filming humpback whales,
which were feeding on krill near the surface.
They would come up almost at 90 degrees with their mouths open.
And the whole mouth of the whale would come up
and go maybe seven, eight, nine feet in the air
and then close and drop back down again.
And it is an amazing sight.
And there's nothing can prepare you for seeing it in real life.
It's truly remarkable.
When they find a rich swarm of krill,
humpbacks aren't shy about helping themselves.
Just one humpback can devour two tons of krill in a single day.
Fur seals also enjoy the floating buffet.
A krill swarm isn't always easy to find,
but they're usually dense and seemingly endless.
Antarctica is surrounded by ice all year long, even in summer.
And ice is where the emperor penguins make their home.
Dr. Gerald Kooyman remembers
when these extraordinary creatures
first introduced themselves.
The first time I had a visit by emperors,
they came to me, which was stunning in itself.
Who's heard of a wild animal that will come up to you?
But I was sitting at the ice edge at Cape Royds.
And two of them came blasting out through thin ice
and then slid across the ice
and came up onto the thicker ice and then walked over to us.
That whole scene just was so surrealistic
that it still seemed other-planet to me.
And that's one of the captivating things.
And it's been with me ever since...
If there's ever an alien on this planet,
I think it's emperor penguins.
These penguins are returning
from feeding in the ocean.
Having eaten their fill, they're heading back to the colony
to feed their waiting chicks.
They pause nervously some distance from the ice.
A few dive down to have a look.
They can't be happy with what they see...
a leopard seal lying in wait.
They're voracious predators, the most lethal in the Antarctic.
But they almost always hunt at the water's edge,
so their prey is safer on the ice than in the sea.
Sensing a window of opportunity, the penguins go for it.
Cameraman Doug Allan was amazed
at how unafraid the emperors were.
Unlike the smaller penguins,
emperors are actually quite confident divers.
I would be swimming with the camera in front of me,
and the emps would just be coming alongside
and cutting across and going into the depths.
The visibility also allowed me to stand back from the ice edge
and get these lovely shots
where they come screaming up from the depths,
trailing bubbles behind them,
and then disappearing, popping out of the surface,
and landing onto the ice on the top.
Safe on the ice,
they still face a long trek home to the colony,
where they'll need to find and feed their chicks.
In the Antarctic winter,
when female emperor penguins head for open water to feed,
their colony can be hundreds of miles from the sea.
But in summer, when the sea ice is gone,
it's a much shorter commute.
In the spring, both penguin parents feed their chicks.
One stays in the colony while the other goes off to feed.
These returning penguins are so stuffed, they can hardly walk.
No predator can reach them once they're on the ice,
so they're in no hurry.
There are about 60,000 penguins in this colony.
Earlier in the spring, each returning mother
had to somehow find her own chick amidst this seeming chaos.
This intricate rite of recognition
fascinates Dr. Martha Holmes.
A female emperor penguin coming back to the colony
will be relying totally on the male's call.
She won't have ever seen her chick.
She won't ever have heard it.
The male and the chick bond will be very strong.
But the female won't know.
And she'll come back solely to listen out for
and to call for her male partner.
Only when they get together will she start listening
to the chick he's got on his feet.
Then she and the chick will form a very, very strong bond,
again, based on calls.
The cries of the chick
prompt the adult to regurgitate a mouthful of fish.
With one well-fed parent returning,
its mate can now go to the sea to feed.
Though hungry, they know there's peril looming in the water.
They bunch together at the edge of the ice.
It seems no one wants to be the first to dive in.
Sometimes a leopard seal will venture out onto the ice
to try and grab a straggler.
But the predators are more successful
when they wait for the meal to come to them.
One hides behind a corner of ice.
With the leopard seal out of sight,
some of the emperors feel the time is right
to take the plunge.
A first wave escapes.
Once they're in the open water, they're safe.
But the seal has come out of hiding.
And camouflaged by the bubbles, he makes a stealth attack.
The odds are in the seal's favour to catch at least one easy meal.
With the seal temporarily occupied,
the rest of the penguins make a dash for the open sea.
As the Antarctic winter descends,
these adults will return to walk across the newly formed ice
and brave another winter on the frozen sea.
But how long will the sea remain frozen?
The Arctic ice cap is melting at an alarming rate
and may disappear altogether by the end of the 21 St century.
Antarctic ice shelves are disintegrating,
and glaciers are retreating.
There can be little doubt
that the effects of this climate change
will be felt by animals living in these environments.
Polar bears are totally dependent on sea ice
and really struggle when they don't have sea ice to live on.
If we stretch that summer period,
if we send them into their dens stressed
because they haven't had the autumn period of sea ice
in which to feed up
before they go into their dens to give birth,
then the bottom is going to fall out of the population.
If we carry on the way we're doing,
then polar bears could very well be extinct
within the next 50 years.
I mean, who knows where it's going to end up?
From a personal point of view, it's an absolute tragedy
that we are potentially responsible
for a loss of such a magnificent habitat
and the species that go with it...
the polar bear, for one.
It's very hard to take that on board...
that we've done it and it's happened so quickly.
I do have two small children, and it makes me very, very sad
to think that they might not ever see
a polar bear in the Arctic.
Very sad indeed.
Our planet is constantly evolving.
Successful species adapt and survive.
Today animals that live at the ends of the Earth
are facing their greatest challenge yet.
Whether they, or we, can meet it remains to be seen.
It's a very narrow line that you're walking
between frostbite or not frostbite.
And to be able to work 20 feet closer to a polar bear
than someone else might be happy to do.
But because you're 20 feet closer,
the close-ups have that bit more bite.
It's 5:00 in the morning, and it's the 18th day of the shoot.
And I think we've just cracked it.
Met a female there with a cub.
And she did quite a lot of pouncing
about 30, 80 meters away.
Just a nice sort of distance.
And you know what she did when she was finished?
She was so relaxed, she sat down and gathered the cub into her
and suckled her head under cover.
When you get something like that, it's incredible.