It's the end of a long arctic winter.
A mother polar bear emerges from her den deep beneath the snow.
She's endured months of freezing temperatures to give birth
to her cubs.
Ahead of them is the adventure of a lifetime.
To survive, the polar bear cubs must follow their mother
on an incredible 400 mile trek
to the edge of the North Pole's pack ice.
It's the greatest challenge of their young lives.
They'll encounter strange creatures...
..brave treacherous ice...
..perilous seas...
..and threatening males.
It's a journey full of surprises...
..as they learn to thrive in a frozen world.
This is a dramatized story based on the extraordinary
adventures of nature's Snow Bears.
High on the southern slopes of the mountains,
deep snowdrifts kept their den safe from winter storms.
The downside of their location is, well, getting down.
One cub seems fearless...
..his sister is a little less confident.
But to get down safely this cub must trust her mother.
Her reassurance goes a long way.
CUB CALLS
There are no nursery slopes when you are 1,000 feet up.
And with every step the slope becomes increasingly treacherous.
Tiny paws are no match for powdery snow.
The nervous cubs need some tough love.
However there is an easier way down...
..if they can just get the hang of it.
After seven months in the den, the soft fresh snow must be bliss.
MOTHER GRUNTS
As the cubs' confidence increases, so does the fun.
Halfway down, and the cubs are ready for a break.
Their mother's milk is almost a third fat -
high-energy fuel for their adventure ahead.
After months of winter darkness,
the sun's return to Svalbard marks a turning point.
For the bears, it means leaving their island.
When the ice melts in spring, the seals vanish with it,
so they must follow their prey north.
The first leg will be to walk 250 miles on the frozen sea
that hugs the coastline.
They'll pass the great glacial fjords,
before reaching the northern tip of the island.
Here they'll venture onto the floating sea ice to cover
the final 150 miles.
Their destination - the seal-rich edge of the pack ice
surrounding the North Pole.
But if they don't leave the island in time, the sea ice will be gone
and they could be marooned here for the summer.
With little to eat, the cubs would be unlikely to survive.
For mothers with cubs it's not just the melting ice that's a threat.
A large male.
He's searching for a mate
and they sometimes kill cubs so they can have a family of their own.
The cubs sense the danger.
Their mother blocks his path...
..but the male sees this as an invitation.
CUBS CALL
MALE GROWLS
But she has a plan - lead him as far from her cubs as possible.
On the slopes she's faster and more agile.
She's soon giving him the run-around.
CUBS CALL
MALE GROWLS
Courting males will stalk females for many weeks.
CUBS CALL
He shadows her closely.
Somehow she must give him the slip.
CUB CALLS
But he's not the only one looking for a mate.
Rivalry is always fierce among the males.
He won't give her up without a fight.
THEY GROWL
She takes her chance to sneak away.
Bears sometimes fight to the death over females.
Now to make good their escape.
But a quick getaway isn't easy.
One cub realises the urgency...
..but the other is struggling.
Luckily, there is an easier way.
Finally the rival is driven off.
The amorous male may have won the fight, but he's lost his prize.
The family can't afford any more hold-ups.
For the cubs, the journey north is full of new experiences.
Svalbard reindeer are the world's smallest, but that doesn't
make them easy to catch,
so they're not on this mother's menu.
These little reindeer survived the winter by eating lichens
buried under the snow.
But there's no time to stop and stare - they're on a tight schedule.
Heading north, they hug the frozen coastline for speed.
Adult bears can travel 50 miles a day,
but for the cubs even ten miles is a struggle.
They are tired and can walk no more.
At three months old they need six rest-breaks a day.
The male has picked up their scent.
Polar bears will pursue females over vast distances.
And here, there's no covering your tracks.
They must get moving,
but their mother hasn't eaten for seven months
and is weak with hunger.
A ringed seal...
..a chance for the cubs to have a hunting lesson.
Stealth and complete silence are essential.
The cubs are trying their best to stay interested.
It doesn't last.
Time for a bit of discipline -
polar bear style.
CUB CALLS
Luckily, the sea ice is rich in seals.
A naive young pup.
He's unlikely to have ever seen a bear.
She treads gently,
not easy when you weigh almost a quarter of a ton.
The ice soon gives her away.
The mother seal tries to warn her pup.
The mother bear has other ideas.
The pup remains blissfully unaware.
A last desperate warning.
Message received.
A set back -
but she can't afford to give up.
Every 30 minutes, the seals must take a breath
and she'll be waiting.
This lesson is all about patience.
The female cub seems to be taking the lesson seriously.
One day she'll have her own young to feed.
Her brother prefers making snowballs.
At last, the waiting is over...
..but it's the wrong hole.
Even the experts can get it wrong.
Still hungry, they must keep hunting.
The bears aren't the only carnivores
trying to scratch a living on the island.
Arctic foxes get through the winter scavenging for scraps
and surviving on their food stores.
The warmer spring air means the good times are on their way.
Unlike the bears, they can't wait for the ice to melt.
The summer will bring out the nesting birds they prey on.
For the cubs, a break from walking is always welcome.
FOXES SQUEAL
But their mother senses a different opportunity.
One of the foxes is digging up his winter food stores.
Leftovers are his insurance policy against starvation.
But his secret is out.
In times of need,
polar bears aren't beneath stealing.
It's a welcome snack for the mother and the cubs' first taste of meat.
Foxes scavenge from polar bears,
perhaps it's only fair that they return the favour.
FOX CALLS
The Arctic fox spots another intruder.
The amorous male is back.
She must think quickly.
She can't outrun him on the flat coastal ice.
She must lead the cubs up and over the mountains.
On the steep slopes
the massive male will struggle to keep up with the more nimble family.
At twice the weight of the female, it's heavy going.
But with his prize in sight he is not giving up.
Nearing the summit,
the family have become trapped.
The male sees his chance.
The cubs are panicking.
CUB CALLS
To escape, they must somehow scale the wall of ice and snow.
But he's matching them step for step.
The stronger male cub is keeping up.
His sister struggles.
Their mother has paved the way,
now it's all down to her cubs.
With one last effort, the little one is up.
But the male is grappling with the steepest part.
Now SHE has the advantage.
Time to strike.
For the male,
there's no dignified way to do this.
HE GRUNTS
The family are safe,
but climbing over the mountain has cost them precious time and energy.
The mother can see that the ice is starting to melt,
and there's still a long way to the end of the island.
Best to take the quickest way down.
Looking for a meal, the family head for the sea ice.
But the conditions are different here.
The seals can be found hiding out in chambers under the snowdrifts.
But it's no problem - she can still smell a seal under
a metre of snow.
Even the Arctic fox can see she's onto something.
Once located, it's a case of smash and grab.
And for the cubs, it's watch and learn.
Getting it right demands precision and experience.
This is it - the big one.
Or maybe not.
But there's no shame in failure -
only one in ten hunts succeed.
Triumph at last.
These cubs are about to get their first taste of fresh seal.
It's her first proper meal for seven months
and it couldn't have come at a better time.
The tip of the island is still two weeks' walk away.
MOTHER GROWLS, FOX CALLS
The fox will have to wait his turn.
CUB GROWLS
With full bellies, the family make good progress.
But as the days warm, the cycle of melt and freeze
has turned the frozen sea into an ice rink.
Adult bears have rough, furry footpads that give a nonslip grip.
Cubs are not so well-equipped.
But on thin ice it's their mother who's in difficulty.
She tries to spread her weight...
..but ultimately something has to give.
The summer melt has arrived early.
And the state of the ice is a sign that time is running out.
With the sea ice vanishing, the polar bear family's chances
of getting safely off the land fade too.
But they have no choice - they must keep going.
Shattered by the pace of the journey,
the cubs need some time to recover.
Ahead is one of the most dangerous parts of the journey -
the glacial fjords.
It's a treacherous place in spring,
as active glaciers become increasingly unstable.
The mother looks for a safe route across,
while the cubs stay back.
But something's wrong.
RUMBLING
Thousands of tonnes of carving glacier
create a wall of water, pulverizing the sea ice.
Somehow she survived...
..but in the chaos she's lost her cubs.
She's picked up a scent.
And on an iceberg, signs of life.
Her cubs.
Undeterred, the family move on -
they need to get out of here.
With the glacial fjords behind them, they are nearing the tip
of the island.
They've made it, but exposed rocks are not a good sign.
The ice flows, which provide safe onward passage for polar bears,
have melted away.
The mother faces a dilemma -
drowning is the greatest risk her cubs face -
so do they swim, in the hope of reaching drifting ice,
or stay put and face starvation?
The arrival of the amorous male makes her decision easy.
She takes her chance,
hoping the cubs can make it to the nearest ice floes.
The crossing is a test of strength and character.
Adult bears can easily swim 60 miles nonstop,
but not the youngsters.
Swimming in their mother's wake means less resistance.
They save valuable energy.
But eventually the cubs have to rest.
Fortunately, salvation is on the horizon.
A small iceberg, cast adrift from the glacier.
But other bears have beaten them to it.
The ice is a good sign though - there will be more.
At last, an ice floe.
The gamble was worth it.
Time to dry off -
the polar bear way.
But it sounds like the family aren't alone here after all.
WATER SPLASHING
Perhaps it's a chance for a meal.
Instead the cubs get their first glimpse of one of
the Arctic's strangest creatures -
the narwhal.
These whales, with their strange tusk
shaped like a mythical unicorn's horn, are a good sign.
They are also heading for the fertile waters of the far north.
Narwhals gather where there's food in abundance.
And where there's fish, there's seals.
On the ice floes,
polar bears have to use a completely different hunting technique.
She must ambush them from the water.
Stealth is essential.
Pinpointing the seal requires deadly accuracy.
For most of the hunt,
her quarry will be out of sight.
She must close the distance without being spotted.
Submerging makes her invisible -
she can calculate the exact spot where the seal can be found.
The seal doesn't suspect a thing...
..except for one small problem...
..or rather two.
The mother wonders where it all went wrong...
..while the cubs reflect on what they've done.
As the summer takes hold, temperatures rise
and the melting drift ice breaks apart.
With the passing weeks,
the distances between rest stops are increasing...
..but the growing cubs are rising to the challenge.
Their mother has picked up a scent.
It's now a case of following her nose.
The scent trail is coming from the carcass of a fin whale.
Its natural death offers both food and rest for the family.
Energy-rich blubber will supercharge the cubs.
But this family are not the only bears heading north.
The male that was shadowing them has also picked up the scent.
He can swim twice as fast as the family
and is making good progress.
The mother knows the whale is a magnet
for other bears, so they must eat quickly.
He's found it...and the family too.
He may just be hungry...
but they can't take the risk.
The family continue their marathon swim.
Then something strange floats into view.
Irresistible to a curious cub.
It's a sleeping walrus...
WALRUS SNORES
..enjoying a little peace and quiet.
He's making the oddest noises.
WALRUS TRUMPETS
The rest of the herd are awake and alert.
Their calves are occasionally taken by polar bears.
But in the water the walruses feel safe.
They even come to investigate the cubs.
Walruses favour the rich waters of the far north -
the bears must be close to their goal.
One of the cubs is tired and tries to hitch a ride,
but he's far too big for that.
The ice floes are getting denser.
Hunting should be good here.
A snoozing seal.
And a look that says,
"Stay put and stay quiet."
Bearded seals weigh around a quarter of a ton.
If the mother can catch it,
this family will have enough energy to fuel their onward journey.
She's as silent as the drifting ice.
Her success feels like a turning point...
..and a taste of things to come.
But a white rainbow warns of a change in the weather.
Their destination is so close now,
but they can't continue.
They just have to sit it out.
As the skies clear,
it seems the storm has pushed their ice floe closer to the pack ice.
In between, dozens of seals play in the narrow channel.
It's this reliable food supply
which makes the edge of the pack ice a polar bear paradise.
One last swim and they'll be home and dry.
But a seal so close is irresistible.
SEAL SNORTS
Seals are superior swimmers
and delight in taunting young bears.
But the big male has also arrived.
He's been on the same journey for 400 miles.
The young cub realises he's in trouble.
It's rare for a male to find a cub alone.
Without his mother, he's defenceless.
She checks on her cubs...
..and realises one's missing.
She can't make out what's happening.
But what seems at first to be aggression
may just be curiosity.
Then, as quickly as it started,
the encounter is over.
The cub is shaken but unscathed.
Through the journey
the male's focus has shifted.
Now he's reached the pack ice,
his thoughts have turned to his stomach rather than the female.
They've made it.
The family can relax at last.
There may be bears everywhere
but there's nothing to fear.
Everyone has a full belly...
..and with food in abundance, no reason to fight or flee.
The family will spend the rest of the summer gorging on seals,
fattening up for the return trip
and for the cycle to start all over again.
Every year across the Arctic,
polar bears make extraordinary journeys
in their constant quest for food.
So life will be one endless adventure
for the Snow Bears.