It’s Memorial Day. You dive into the unheated community pool for the first time this year and immediately come up gasping for breath—the water is freezing! You jump out of the pool as quickly as you can, while your lips turn purple and goose bumps start to form. Maybe you’ll be happy to just sit in the sun for a week or two until the water warms up.

Now imagine you are in northern Alaska. The water temperature is just above freezing and the air temperature is well below 0° Fahrenheit. There’s no way you would want to go swimming. A polar bear can do just that without getting cold at all. First, it has two layers of fur which keep its skin from getting wet and protect it from the cold. It also has a four inch layer of fat, or blubber, under its fur which keeps it toasty warm in the coldest temperatures. The bottom of its feet are covered in fur, and those parts that aren’t furry have a rough surface like sandpaper to keep the polar bear from slipping on the ice. The polar bear is so well insulated that it can actually get overheated after running a short time.

A polar bear can swim as far as 60 miles without stopping, dive 15 feet below the water’s surface and stay under water for about two minutes. It paddles only with its front feet, using its back feet as rudders to steer. A lot of the time it spends in the water is to hunt seals, its favorite food. It will also eat fish, birds, dead animals, berries and vegetation.

Polar bears are not currently considered endangered or threatened. However, many of the areas in which they live are the sites of oil and gas deposits, which may mean further invasion by man into the bear’s habitat. Oil spills and air pollution have already affected the polar bears’ food supply.