The night.
A shadowy world that hides more than half the animals on our planet.
Until now, cameras only offered a glimpse into their lives.
But with next-generation technology,
we can see the night as clear as day.
With cameras a hundred times more sensitive than the human eye...
we can now capture the beauty of night...
in color.
Alien landscapes.
Strange creatures brought to life by the darkness.
Unseen behaviors.
Now we can follow the lives of animals
in Earth's last true wilderness.
The night.
Winter in the Arctic.
By day, the sun barely rises.
And soon it will set.
Plunging this frozen world into darkness for over a month.
And for one arctic resident, it's a time of great change.
This polar bear mother has twins.
She'll look after them for two years,
teaching them all the skills they'll need to survive.
They follow her everywhere.
No easy task.
There's lots to learn.
At the start of winter, there's so little food around,
polar bear moms can lose a kilo of weight each day.
Weak and hungry,
just keeping her cubs safe through the freezing nights ahead
will be her greatest challenge.
And this family is not alone.
Along the Arctic coastline, other hungry bears are gathering.
Waiting for the temperature to drop so low
that even the sea will freeze solid.
Then they'll head out onto the sea ice to hunt for seals,
a vital source of food for these ravenous bears.
But until the big freeze comes,
the mother and her cubs,
and all the other bears, must play a waiting game.
As the arctic winter draws in...
the nights get longer.
And this frozen landscape transforms.
Filming just by the light of the moon...
low light cameras capture this icy world
like never before.
Offering an intimate glimpse
of what polar bears get up to under the stars.
Tonight, the mother's first job is to suckle her hungry cubs.
Her milk is more than 30% fat...
helping the cubs develop the thick blubber they'll need to survive the winter.
Next, it's time for a midnight clean.
Rolling in the snow is how polar bears wash their thick fur.
The cubs copy their mom.
A regular snow bath keeps their coats well insulated.
And tonight, they'll need all the warmth they can get.
In the arctic winter,
storms can strike with little warning.
And for young cubs, these blizzards can prove fatal.
But polar bears aren't the only animals
that are active through the freezing winter nights.
In snowy forests on the edge of the Arctic Circle,
an equally tough little creature emerges in the moonlight.
The mountain hare.
To avoid predators, they only come out after dark.
By the start of winter, their coat has changed from brown to white.
The perfect camouflage.
This young male is having a midnight snack.
With limited food around, he must feed while he can.
But he's not the only hungry hare here.
Rivals must be seen off.
Competition for food and mates can be fierce.
Their chasing can hit speeds of 40 kilometers an hour.
But when his rival won't back down...
the gloves really come off.
Few punches hit the target.
It's all about who looks the toughest.
Tonight, he emerges victorious.
Giving this nocturnal champion
the best chance of getting through the long winter nights ahead.
Back on the coastline,
the polar bear mother and her cubs hunker down
as the temperatures plummet.
During winter nights, polar cyclones blow in off the ocean
with a wind chill of minus 50 degrees Celsius.
Polar bear cubs are vulnerable to the severe cold.
Only one in two make it through their first winter.
But night cameras show the mother has an ingenious solution.
She digs.
Slowly carving out a shelter
for her cubs to take refuge from the storm.
Polar bear families can spend up to four nights
holed up in dens like this.
It's the only way mothers can keep their precious youngsters alive.
The family must lie low...
until the blizzard has passed.
The storm subsides.
And the family emerge to find the winds have brought great change.
Where once there was ocean,
now there's ice.
As far as the eye can see.
The mother leads her cubs towards the sea ice for the first time.
To start the next chapter of their lives.
In the weeks ahead,
she'll teach them how to survive this frozen landscape
through the long arctic winter.
But she's not the only polar bear mother
exploring this frozen landscape in the darkness.
Far out on the sea ice,
another mom has bigger parenting challenges.
At four years old, her youngsters are nearly fully grown.
Mischievous teenagers.
Low light cameras catch something unusual.
The cubs taking a nighttime dip.
They're already excellent swimmers.
But at this age, the hardest part is learning how to get out.
The first cub has got the hang of it.
But for his brother...
it's more of a challenge.
Finally.
At least no one was watching.
Even with such big cubs, the mother must be on her guard.
At four years old, they're testing their boundaries.
And with large males around, that can be dangerous.
She'll have to keep them close in the nights ahead.
Throughout the long, dark winter,
the night skies over this frozen world
become the backdrop for Earth's most magical light display.
The aurora borealis.
Energy from solar storms
colliding with our atmosphere to make ribbons of light...
more than a hundred kilometers high.
They blaze both night and day.
But we can only see them against the dark night sky.
By late winter,
the darkness starts to give up its hold.
And the sun rises briefly above the horizon
for the first time in weeks.
In the first hours of twilight,
the mother and her older cubs arrive in a frozen glacial bay.
Whilst mom heads off to hunt for seals...
the four-year-olds are free to play.
But not for long.
A lone bear is also in the bay.
Solitary polar bears can be highly aggressive.
But the cubs are curious.
Approaching a stranger is risky.
A fight could lead to serious injury.
But then, what seemed like aggression...
suddenly becomes more playful.
It turns out the stranger is a young female.
And this is all a romantic play fight.
Polar bear rough-and-tumble.
Such tender social behavior has rarely been seen before.
With her cubs rapidly growing up,
this mother's work is almost done.
She's devoted the last four years of her life to looking after them.
In the coming days, her boisterous cubs will leave her.
And next year, these young bears
will face the long, dark nights of winter on their own.
-Ready? -Yeah.
Filming polar bears at night would test the crew to their limits.
And when a polar storm struck on night one,
they got a sense of the challenges they'd face
in the dark weeks ahead.
It's about minus 30 out here at the moment.
And I think we're finding the limits
of what the cameras and equipment can put up with.
So, we've got a long ride home in this.
With the storm chasing them all the way,
they had to rely on their GPS to find their way back to shelter.
The next night, and the search for bears was hijacked
by arctic conditions once more.
Ready!
Currently stuck in the ice. All this is surface water.
Where fresh water runs off the land and onto the sea ice,
it can melt, turning it to slush.
The crew became trapped.
Every move sank them deeper, closer to the ocean beneath.
This is definitely the hardest shoot I've been on.
Just bad weather and no polar bears.
And things were about to get worse.
Overnight, the sea ice, which the bears need to hunt on,
suddenly sheared off and disappeared.
Blown away, far from the shore, taking the polar bears with it.
Even in the frozen depths of winter,
the sea ice here is shrinking.
A change in climate is making the future for polar bears uncertain.
Three weeks into filming,
the crew needed a change of luck.
And there was the smallest glimmer of hope in the unlikeliest of places.
Well, we've gone looking for the bears today,
but looks like a bear's come looking for us.
And made a beeline for our toilet.
Wow. You can actually see teeth marks
and the claw marks where the bear's been.
Could be a nasty surprise while you're on the toilet.
The next night, they caught the culprit red-handed.
Luckily, it was unoccupied at the time.
With bears about, things were finally looking up for the crew.
And soon, their immense efforts were rewarded.
Day 20, and we finally got bears.
And not just one bear.
Got a mother and two cubs.
Finally.
Oh, my God. They look beautiful, man.
After many arctic adventures,
the crew were finally able to capture unique footage
of polar bears under moonlight.
And reveal the secrets of the arctic night like never before.