The oceans of the Earth are all connected. They are truly one "world ocean" which covers about 71 percent of the Earth's surface. The salt water which flows from one part of the ocean to another without hindrance makes up 97 percent of the planet's water supply. Geographers, for many years, divided the world ocean into four parts: the Atlantic, Pacific, Indian, and Arctic Oceans. In addition to these oceans, they also described many other smaller bodies of salt water including seas, bays, and estuaries. It wasn't until 2000 that a fifth ocean was officially named: the Southern Ocean, which includes the waters around Antarctica.

01 of 05 Pacific Ocean Natalia_Kollegova/Pixabay The Pacific Ocean is by far the world's largest ocean at 60,060,700 square miles (155,557,000 sq km). According to the CIA World Factbook, it covers 28 percent of the Earth and is equal in size to nearly all of the land area on the Earth. The Pacific Ocean is located between the Southern Ocean, Asia, and Australia in the Western Hemisphere. It has an average depth of 13,215 feet (4,028 meters), but its deepest point is the Challenger Deep within the Mariana Trench near Japan. This area is also the deepest point in the world at -35,840 feet (-10,924 meters). The Pacific Ocean is important to geography not only because of its size but also because it has been a major historical route of exploration and migration.

02 of 05 Atlantic Ocean Luis Castaneda Inc./Getty Images The Atlantic Ocean is the world's second-largest ocean with an area of 29,637,900 square miles (76,762,000 sq. km). It is located between Africa, Europe, and the Southern Ocean in the Western Hemisphere. It includes water bodies such as the Baltic Sea, Black Sea, Caribbean Sea, Gulf of Mexico, Mediterranean Sea, and the North Sea. The average depth of the Atlantic Ocean is 12,880 feet (3,926 meters) and the deepest point is the Puerto Rico Trench at -28,231 feet (-8,605 meters). The Atlantic Ocean is important to the world's weather (as are all oceans) because strong Atlantic hurricanes often develop off the coast of Cape Verde, Africa and move toward the Caribbean Sea from August to November.

03 of 05 Indian Ocean mgokalp/Getty Images The Indian Ocean is the world's third-largest ocean and it has an area of 26,469,900 square miles (68,566,000 sq km). It is located between Africa, the Southern Ocean, Asia, and Australia. The Indian Ocean has an average depth of 13,002 feet (3,963 meters) and the Java Trench is its deepest point at -23,812 feet (-7,258 meters). The waters of the Indian Ocean also include water bodies such as the Andaman, Arabian, Flores, Java, and the Red Sea, as well as the Bay of Bengal, Great Australian Bight, Gulf of Aden, Gulf of Oman, Mozambique Channel, and the Persian Gulf. The Indian Ocean is known for causing the monsoonal weather patterns that dominate much of southeast Asia and for having waters that have been historical chokepoints (narrow international waterways).

04 of 05 Southern Ocean Yann Arthus-Bertrand/Getty Images The Southern Ocean is the world's newest and fourth-largest ocean. In the spring of 2000, the International Hydrographic Organization decided to delimit a fifth ocean. In doing so, boundaries were taken from the Pacific, Atlantic, and Indian Oceans. The Southern Ocean extends from the coast of Antarctica to 60 degrees south latitude. It has a total area of 7,848,300 square miles (20,327,000 sq km) and an average depth ranging from 13,100 to 16,400 feet (4,000 to 5,000 meters). The deepest point in the Southern Ocean is unnamed, but it is in the south end of the South Sandwich Trench and has a depth of -23,737 feet (-7,235 meters). The world's largest ocean current, the Antarctic Circumpolar Current, moves east and is 13,049 miles (21,000 km) in length.