An ocean is a body of saline water that composes much of a planet's hydrosphere.On Earth, an ocean is one of the major conventional divisions of the World Ocean, which covers almost 71% of its surface. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.The word sea is often used interchangeably with "ocean" in American English but, strictly speaking, a sea is a body of saline water (generally a division of the world ocean) partly or fully enclosed by land. Feel the oceans on the pages of this coffee table book.See the ocean in new light panoramic view. You don't need to travel too far to see how the oceans around the world look. Enjoy the ocean in clear pictures.