Most predators find it too difficult to break through the complex network of branches and mud so the beavers stay protected. Beavers that live in rivers do not usually build lodges instead they create burrows out of the mud along riverbanks. When the lakes and ponds freeze over, beavers swim in the water underneath the ice. They have thick underfur that keeps them well insulted and a thick layer of fat under their skin. Beavers also keep their fur waterproof by rubbing an oily substance on their fur that is secreted from scent glands.
Beavers have large webbed hind legs that act as paddles when they swim through the water.
They have a large flat tail that helps them steer through the water. They also have clear eyelids that make it possible for them to open their eyes underwater. These animals can stay under water for as long as 15 minutes because of their specially adapted lungs. Beavers have wide, hairless, flat tails. Their tails are not only used for steering but also for balance, warning signals, and fat storage.