List of the oceans of the world

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 70.9% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 metres (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Scientists estimate that 230,000 marine life forms of all types are currently known, but the total could be up to 10 times that number. 

The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria. These divisions are (in descending order of size):

• Pacific Ocean, which separates Asia and Australia from the Americas
• Atlantic Ocean, which separates the Americas from Eurasia and Africa
• Indian Ocean, which washes upon southern Asia and separates Africa and Australia
• Southern Ocean (proposed) or Antarctic Ocean, sometimes considered an extension of Pacific, Atlantic and Indian Oceans, which covers the waters that surround Antarctica.
• Arctic Ocean, sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon northern North America and Eurasia. 

The ocean has a significant effect on the biosphere. Oceanic evaporation, as a phase of the water cycle, is the source of most rainfall, and ocean temperatures determine climate and wind patterns that affect life on land. Life within the ocean evolved 3 billion years prior to life on land. Both the depth and distance from shore strongly influence the amount and kinds of plants and animals that live there. 

The Pacific Ocean is the largest of the world's five oceans, followed by the Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean. The ocean covers 71 percent of the Earth's surface and contains 97 percent of the planet's water, yet more than 95 percent of the underwater world remains unexplored.  The ocean and lakes play an integral role in many of the Earth's systems including climate and weather. The ocean supports the life of nearly 50 percent of all species on Earth and helps sustain that life providing 20 percent of the animal protein and five percent of the total protein in the human diet. 

The area of the five oceans is:

1. Pacific (155,557,000 sq km)
2. Atlantic (76,762,000 sq km)
3. Indian (68,556,000 sq km)
4. Southern (20,327,000 sq km)
5. Arctic (14,056,000 sq km