Polar bears are large mammals. They can walk on ice without slipping and they swim silently underwater.
Polar bears measure around 8 feet (2.5 metres) in lenght, but newborn cubs are the size of a guinea pig. Adult male polar bears weigh from 775 to 1,500 pounds (350 to 680 kilograms). Females are considerably smaller, normally weighing from 330 to 550 pounds (150 to 250 kilograms).