OCEANS

The earth’s oceans make up more than 70% of its total surface area. More than half of this area of salt water is more than 9000 feet deep!
There are actually just three distinctly separate oceans in the world today; the World Ocean, the Black Ocean and the Caspian Sea. The largest ocean on earth is the World Ocean, measuring in at an immense 361 million square kilometers. The World Ocean is continentally divided into five smaller parts, which include the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Arctic Ocean and the Antarctic Ocean. Smaller portions of these oceans are typically classified as either seas, gulfs or straits.
The Mediterranean Sea unofficially became the world’s fourth ocean when the sea’s only outlet to the World Ocean, the Strait of Gibraltar, was closed due to the movement of the African continent.
The oceans of the world are home to the vast majority of the plant and animal species on earth, millions of which have yet to be

Salty Oceans?
Oceans make up about 70 percent of Earth’s surface and contain lots of different salts: sodium, chloride, sulfate, magnesium, calcium, potassium, bicarbonate, and bromide. These salts enter the ocean through rivers, which, before entering pass over rocks and soil, and pick up salt along the way.
This salt builds up in the ocean because the only way water can leave the ocean is through evaporation. And when the water evaporates it doesn't take the salt with it. So you end up with less water, and the same amount of salt, resulting in a pretty salty sea.
The same thing can happen to a smaller, landlocked body of water, such as the Great Salt Lake in Utah, where water evaporates quickly in the desert climate—the lake has dropped 20 feet since 1849. A favorite pastime for visitors is to float on the lake like a cork, because the high salt content makes people more buoyant.

ANCIENT OCEANS
Continental drift has reconfigured the Earth's oceans, joining and splitting ancient oceans to form the current oceans. Ancient oceans include:
Bridge River Ocean, the ocean between the ancient Insular Islands and North America.
Iapetus Ocean, the southern hemisphere ocean between Baltica and Avalonia.
Panthalassa, the vast world ocean that surrounded the Pangaea supercontinent.
Rheic Ocean
Slide Mountain Ocean, the ocean between the ancient Intermontane Islands and North America.
Tethys Ocean, the ocean between the ancient continents of Gondwana and Laurasia.
Khanty Ocean, the ocean between Baltica and Siberia.
Mirovia, the ocean that surrounded the Rodinia supercontinent.
Paleo-Tethys Ocean, the ocean between Gondwana and the Hunic terranes.
Proto-Tethys Ocean,
Pan-African Ocean, the ocean that surrounded the Pannotia supercontinent.
Superocean, the ocean that surrounds a global supercontinent.
Ural Ocean, the ocean between Siberia and Baltica.