Fur
A polar bear's fur is about 2.5 to 5 cm (1-2 in.) thick and water repellent. A layer of guard hairs covers a thick wooly layer of under-hair. These guard hairs are shiny, clear, and smooth, allowing the hairs to trap heat from the sun. A good way for polar bears to keep warm!

Fur from a Polar Bear.

Blubber
Beluga whales, walruses and seals have a thick layer of fat, called blubber, just below the skin, helping to insulate them from the cold. The blubber also stores energy for times when the food supply is scarce.

Skin from a Pacific Walrus, blubber is underneath.

Camouflage
The winter coat of the arctic fox is stark white, helping it to blend in with its snowy habitat. Only in the summer does its coat turn brownish gray.

Fur from an female arctic fox next to a rock.