Oceans
The dictionary defines ‘Ocean’ as the vast body of water that covers 71 percent of the earth. There are four named oceans: the Atlantic, Pacific, Indian, and Arctic ... and the Southern (Antarctic) is a newly-named fifth ocean.
Sea is defined as a body of salty water that covers 71 percent of the earth and is partly surrounded by land. There are about 50 seas around the world. The sea moderates earth's climate and has important roles in the water, carbon and nitrogen cycles.