Dutiful mothers, female polar bears usually give birth to twin cubs, which stay with her for more than two years until they can hunt and survive on their own.

Polar bears roam the Arctic ice sheets and swim in that region's coastal waters. They are very strong swimmers, and their large front paws, which they use to paddle, are slightly webbed. Some polar bears have been seen swimming hundreds of miles from land—though they probably cover most of that distance by floating on sheets of ice.