Polar bears are insulated by two layers of fur. Their fur appears to be white but is actually transparent. The white color results from light being refracted through the hair strands.
If properly nourished, polar bears also have a thick fat layer. Compact ears and small tail prevent heat loss. Polar bears have more problems with overheating than they do from the cold (which can plummet to -40 degrees C!). Especially when they run!
Polar bears have a great sense of smell. They can detect seal scent from almost one mile away! Their powerful claws can haul a 150-200 lb seal from the water.