Oceans cover more than 70% of Earth’s surface. About 97% of Earth’s water is contained in oceans and seas. The five oceans—the Pacific, Atlantic, Indian, Southern, and Arctic—are all connected and form an enormous mass of water. Seas are smaller bodies of salty water within the oceans. The oceans are salty, which makes them unsuitable for drinking. Most of the salt comes from minerals from rocks and soil that have been washed from the land and carried into the oceans by rivers. The minerals are mostly chloride and sodium, which combine to make salt. Most of our table salt comes from the oceans. The salinity, the amount of salt, varies in the oceans. Oceans in warm, dry areas are more salty than the oceans in cold climates, such as near the North and South Poles. That’s because ocean water in warmer areas evaporates quicker, leaving more salt behind. The saltiest water in the world is in the Red Sea, which is almost entirely surrounded by deserts. Tides Tides, waves, and currents cau...