Surprisingly, the polar bears' skin color is black. The bears' black skin absorbs heat from the sun and soaks up as many of the sun's rays as possible to help in temperature regulation in the bears' freezing environment. Under the skin is a thick layer of fat in healthy individuals which provides insulation from the weather. The fur, which appears to be white, is actually made up of almost colorless, almost transparent hairs. The long, coarse guard hairs are hollow, allowing the warming rays of the sun to reach to the dark skin that acts as a solar heat collector. With these characteristics suited for their environment, they are more in danger of hyperthermia (over-heating) than hypothermia (freezing). Even in the coldest Arctic weather, the polar bear is very comfortable.

The air-filled hollow guard hairs also help insulate them from extreme temperatures. The hairs of the thick undercoat are similarly nearly colorless but are not hollow. Reflection of the sunlight from the densely packed, almost colorless hairs makes polar bears appear to be white in a sort of optical illusion.

The hairs are not fully transparent because they contain keratin. Keratin can seem almost clear but is actually off-white, the same as your fingernails that are also composed of keratin. Viewed side-on, the hairs appear colorless; viewed lengthwise (as if one were looking down a telescope) the hairs no longer appear transparent. For many years, scientists operated under the theory that the individual hair might act as fiber optics taking sunlight directly to the skin. This has recently been proven to be incorrect.

Their skin is white, and the texture is fur.

The poar bears skin is black, and the fur is see-through, but the light reflecting off of it makes is white

Polar bears have transparent fur over black skin.

Reflection of the sunlight from the densely packed transparent hairs makes polar bears seem to be white.

The very white bear has a black skin (under all that white fur). You can see it at the nose.

The skin color is actually black, but the fur is yellowish-white.

The skin of a polar bear is actually black. While it appears to be white, the fur of a polar bear is actually transparent.