Polar bears depend on the ocean as their means of travel.
The polar bear ( ursus #Latin maritimus #Latin ) is a carnivorous bear whose native range lies largely within the Arctic Circle , encompassing the Arctic Ocean , its surrounding seas and surrounding land masses . Although most polar bears are born on land , they spend most of their time on the sea ice . Because of their dependence on the sea ice , polar bears are classified as marine mammals ; an alternative basis for classification as marine mammals is that they depend on the ocean as their main food source .