Polar bears are famous for being white but their skin is actually black and their fur is clear.
Covering a polar bear’s black skin is fur that is hollow and has no pigment. The fur gives a polar bear the white appearance despite being transparent due to the way the light hits it and diffuses similar to how snow appears to be white even thought it is just clear frozen water.
Polar bears also appear whiter the cleaner they are. Oils accumulate on their skin from the seals they eat and often result in the fur turning a yellowish color.