So,what keeps the polar bears so toasty in the Arctic deep freeze? Their best protection from the cold is their thick, white fur coat that keeps them warm even on the coldest days.The fur coat has two layers.There is a thick,soft underlayer of fur next to their skin and an outer layer of long,thinner hairs called guard hairs.The guard hairs are hollow tubes like drinking straws that direct the sun's rays to the bear's skin.A polar bear looks white,but under its fur the skin is black.Dark skin can absorb more heat than light skin,so it helps keep the polar bear warm.Another way a polar bear copes with the cold is with built in insulation.Polar bears have a layer of blubber,or fat,under their skin that can be more than four inches thick.Like other kinds of insulation,blubber stops heat from getting out.The bear's thick fur,dark skin,and fat keep it warm in icy water as well as on land.