Polar bears are champion long-distance swimmers among land mammals, and it is not uncommon to find them at sea as far as 50 miles from land or an ice floe.

• 在陆地哺乳动物中，北极熊无疑是长距离游泳冠军。人们经常在距离陆地或者大块浮冰50英里远的地方看到它们。