It is so cold up on the Arctic Ocean where polar bears live (and also where the North Pole is) that the ocean is covered with ice! Most animals couldn’t survive up there, but polar bears can! How they do it is pretty cool.
They have very thick fur and a lot of fat, called "blubber," that keeps them warm. They also have very wide feet that help them spread their weight out so they don’t fall through the ice. Otherwise, the ice might crack and they might get stuck in the water.
Polar bears also like to hunt seals, which live under the ice. Polar bears have much longer necks than most other bears. This lets them find holes in the ice and reach their heads far down to catch seals.
Their bodies are built for a life on ice! In fact, if they lived anywhere warmer, they could overheat, which is not very healthy for them at all!