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Earth seen from space; the Pacific Ocean is in viewEarth seen from space; the Pacific Ocean is in view The oceans cover more than 360 million square kilometres (139 million square miles) of the Earth’s surface, approximately 71% of its total area. More than 1350 million cubic kilometres (324 million cubic miles) of water is contained within it, representing nearly 97% of the Earth’s entire supply. The oceans hold enough salt in them to cover Europe to a depth of 5 kilometres (3 miles). There are five oceans: in order of size, the Pacific, Atlantic, Indian, Arctic and Southern. We often use the word "sea" to mean ocean, although, strictly, seas are smaller parts of the ocean partly enclosed by land, for example, Mediterranean Sea or North Sea.

Oceans of the worldOceans of the world
Ocean currentsOcean currents

Moving waters

The ocean waters are not still, but move in tides and currents. Tides shift the water daily under the gravitational pull of the Moon. Currents, great flowing bands of water, swirl around the globe, swept along by the winds. Some are cool and and some are warm currents: together they have a significant effect on the climates of lands bordering the ocean. 

The ocean floor

The oceans cover approximately 71% of the Earth's surface area.

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