1. Pacific Ocean
The Pacific Ocean is the largest ocean. It is also the largest single geographic feature on Earth. The Pacific Ocean is the deepest ocean - its average depth is 12,927 feet. According to the CIA World Factbook, the Pacific Ocean covers 60,060,894 square miles, making it about 15 times the size of the United States. The Pacific Ocean is bounded by 84,297 miles of coastline, with the western coast of Canada and the U.S. and South America to the east, the coasts of Asia, and Australia to the west, and the more newly-designated (2000) Southern Ocean to the south. The Pacific Ocean is also the ocean with the most islands - it contains over 30,000 islands. There is also a hotbed of earthquake and volcanic activity around the Pacific, known as the "Ring of Fire".
A large underwater ridge, known as the East Pacific Rise, runs along the bottom of the ocean. This is one portion of the mid-ocean ridge system that occurs on the ocean floor where where plates of the Earth's surface move apart and new oceanic crust is formed.
2. Atlantic Ocean
The Atlantic Ocean is smaller and shallower than the Pacific Ocean. It is bounded by North and South America to the west, Europe and Africa to the east, the Arctic Ocean to the north and the Southern Ocean to the south. It covers 29,637,974 square miles (making it about 6 times the size of the United States) and is bounded by 69,510 miles of coastline (Source: CIA World Factbook.
One large underwater feature of the Atlantic Ocean is the Mid-Atlantic Ridge, a plate boundary in the Earth's crust that runs down the middle of the Atlantic Ocean.
Like the Pacific Ocean, it is difficult to list the marine life that live in the Atlantic, because of its large size and diversity of habitats. Whales, sirenians such as manatees, pinnipeds, sea turtles, pinnipeds, fish, invertebrates and plankton all live here.
3. Indian OceanThe Indian Ocean is the third-largest ocean, and covers 26,469,620 square miles, which makes it about 5.5 times the size of the United States. It is bounded by Africa to the west, Asia and Australia to the east, and the Southern Ocean to the south, which makes up 41,337 miles of coastline.
4. Southern, or Antarctic OceanThe Southern, or Antarctic, Ocean was designated from parts of the Atlantic, Pacific and Indian Oceans in 2000 by the International Hydrographic Organization. This occurred after scientific research realized that an ocean current known as the Antarctic Circumpolar Current, which flows around Antarctica from the west to the east, forms an important boundary from the other oceans. This is the fourth largest ocean, and covers 7,848,299 square miles. This ocean isn't always recognized as a separate ocean, but the abundance of marine life that live in this ocean and migrate there to feed cause it to be a subject of scientific research, and make it notable to those interested in marine life. A large portion of this ocean was designated as a whale sanctuary by the International Whaling Commission in 1994, although some whale hunting still occurs there by the Japanese, who hunt primarily minke whales in a controversial hunt for scientific research purposes.
In addition to whales, other marine life in the Southern Ocean include pinnipeds, fish, invertebrates and seabirds such as the much-loved penguins.
5. Arctic Ocean
At a size of 5,427,052 square miles, the Arctic Ocean is the smallest ocean. It lies mostly north of the Arctic Circle, and is bounded by Europe, Asia and North America.
The Arctic Ocean is home to a variety of marine life, including polar bears (who, while they don't live solely in the water, may be considered marine mammals - e.g., they are protected under the Marine Mammal Protection Act.), cetaceans, fish and invertebrates. Click here to learn more about the species that inhabit the Arctic Ocean.
- CIA - The World Factbook. Accessed December 29, 2011.
- Coulombe, D.A. 1984. The Seaside Naturalist. Simon & Schuster: New York.
- MarineBio.org. Little Known Facts About The Ocean. MarineBio.org. Accessed December 30, 2011.
- Tarbuck, E.J., Lutgens, F.K. and Tasa, D. Earth Science, Twelfth Edition. 2009. Pearson Prentice Hall: New Jersey.
- University of Delaware. 2002. Pacific Ocean. Accessed December 30, 2011.
- U.S. Fish and Wildlife Service. 2011. Polar Bear. Accessed December 30, 2011.