NARRATOR: Ice melts, cracks, and pulls away from the mainland.
The water is still a bone-chilling 35 degrees,
cold enough to freeze a human in a matter of minutes,
but perfect for young polar bears out with their mom.
For most of the year, their world is ice.
Open water is a novelty, which is why what you're about to see
is so rare.
These two practice a type of swimming usually
seen in underwater mammals.
It's called porpoising.
[folk music]
[bears roaring]
Polar bears live on an opposite schedule
to other animals in Alaska.
Winter is when they hunt on the ice and eat.
Summer melts their ice.
They have no choice but to fast.
They swim and laze in the sun with empty bellies.