An ocean is a large area of salt water between continents. Oceans are very big and they join smaller seas together. Together, the oceans are like one “ocean”, because all the “oceans” are joined. Oceans (or marine biomes) cover 72% of our planet. The largest ocean is the Pacific Ocean. It covers 1/3 (one third) of the Earth’s surface. Big and small fish of different types are found in oceans. Crabs, starfish, sharks, whales, etc. are found in oceans.

The smallest ocean is the Arctic Ocean. Different water movements separate the Southern Ocean from the Atlantic, Pacific, and Indian Oceans. The Southern ocean is also called the Antarctic Ocean, because it covers the area around Antarctica. Older maps may not use the names Arctic Ocean and Southern Ocean.

The deepest ocean is the Pacific ocean. The deepest point is the Mariana Trench, about 11,000 meters (36,200 feet) deep. The deep ocean is characterized by cold temperatures, high pressure, and complete darkness. Some very unusual organisms live in this part of the ocean. They do not require energy from the sun to survive, because they use chemicals from deep inside the Earth.

The Atlantic Ocean is the world’s second largest ocean. It covers a total area of about 106,400,000 square kilometers (41,100,000 square miles). It covers about 20 percent of the Earth’s surface. It is named after the god Atlas from Greek mythology. Its name means “Sea of Atlas.”

Extent of the Atlantic Ocean

The Arctic Ocean is the ocean around the North Pole. The most northern parts of Eurasia and North America are around the Arctic Ocean. Thick pack ice and snow cover almost all of this ocean in winter and most of it in summer. An icebreaker or a nuclear-powered submarine can use the Northwest Passage through the Arctic Ocean to go between the Pacific and Atlantic oceans.

The ocean’s area is about 14.056 million km2, which is the smallest of the world’s 5 oceans, and it has 45,389 kilometers (28,203 miles) of coastline. The central surface is covered by ice about 3 meters (9.8 feet) thick. The biology there is quite special. Endangered species there include walruses, whales, and polar bears. Year by year the Arctic ocean is becoming less icy.

Map of the Arctic Ocean

The Indian Ocean is the third largest of the world’s oceanic divisions, covering 70,560,000 km2 (27,240,000 sq mi), approximately 20% of the water on the Earth’s surface. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, and on the south by the Southern Ocean or, depending on definition, by Antarctica. It is named after India.

The deepest point in the Indian Ocean is in the Java Trench near the Sunda Islands in the east, 7500 m (25,344 feet) deep. The average depth is 13,002 feet deep. The majority is in the southern hemisphere.

Extent of the Indian Ocean according to The World Factbook


The Pacific Ocean is the body of water between Asia and Australia in the west, the Americas in the east, the Southern Ocean to the south, and the Arctic Ocean to the north. It is the largest named ocean and it covers one-third of the surface of the entire world. It joins the Atlantic Ocean at a line drawn south from Cape Horn, Chile/Argentina to Antarctica, and joins the Indian Ocean at a line drawn south from Tasmania, Australia to Antarctica.

As the Atlantic slowly gets wider, the Pacific is slowly shrinking. It does this by folding the sea floor in towards the center of the Earth.

The Pacific Ocean

The Southern Ocean is the ocean around Antarctica. It was a new term in geography officially created in 2000. It means the waters of the Atlantic, Pacific, and Indian Oceans around the continent of Antarctica out to sixty degrees south latitude. Some people call this ocean the Antarctic Ocean.

Southern Ocean around Antarctica (looking up at the bottom of the Earth)


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