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The Pacific Ocean

The world's largest geographic feature, the Pacific Ocean covers about one-third of the earth's surface. The area of the Pacific is greater than that of all of the continents combined, and it makes up nearly half of the area covered by the earth's oceans.

The Pacific Ocean borders Asia and Oceania to the west, North and South America to the east, and Antarctica to the south. Some of the major marginal seas of the Pacific are the Bering Sea, the Sea of Okhotsk, the Sea of Japan, the East China Sea, the South China Sea, the Coral Sea, the Tasman Sea, the Ross Sea, and the Gulf of California. The Pacific also contains more islands than the total number in the rest of the world. Many of these islands form archipelagoes that are the tops of submerged oceanic ridges, such as the Aleutian Islands in the northern Pacific.

The Pacific is not only the largest ocean but also the world's oldest and deepest, reaching its greatest depth at the Marianas Trench, near Guam. Its most striking submarine feature is the dozen or so deep trenches that are found around its margins. The sea floor also has great abyssal plains and a major spreading centre ridge called the East Pacific Rise.

Most of the geological activity of the Pacific occurs around its edges. In fact, the Pacific "ring of fire" contains more than 80 per cent of the earth's active volcanoes and most of its earthquake activity. The ocean covers several of the earth's crustal plates. The warm vents and geysers rising from the plate boundaries are prime habitats for rich underwater life.

The Pacific was given its name because of the tranquillity of its waters, although it is occasionally swept by typhoons, and a number of strong currents circulate beneath the surface. The influence of the icy Antarctic continent and the smaller ratio of land to sea in the southern Pacific means that water temperatures there are slightly lower than in the northern Pacific. The cold water generated around the South Pole sinks and then circulates northwards to form a cold, deep current from Antarctica to Japan.

The atmospheric and oceanic phenomenon of El Niņo in the Pacific creates unusually warm ocean conditions, causing climatic disturbances of varying severity. The warm southward current, often accompanied by fluctuating air pressure and wind patterns, occurs each December but is exceptionally intense every seven to ten years. El Niņo of 1982 and 1983 was the most severe of the 20th century. El Niņo affects climates around the world for more than a year. Droughts plague some areas, while others are battered with heavy rains. Birds and fish die or are forced to leave their natural habitat during El Niņo.

The commercial importance of the Pacific Ocean has increased significantly since 1920 with the opening of the Panama Canal, which links the Pacific to the Atlantic Ocean. Fishing along the east coasts and near the Equator is a significant industry. The Pacific has also begun to be exploited for its vast mineral resources. The continental shelves off the coasts of California, Alaska, China, and the Indonesian area are known to contain large reserves of petroleum. Patches of the ocean floor are covered with manganese nodules, potato-sized concretions of iron and manganese oxides that sometimes also contain copper, cobalt, and nickel. Programmes are under way to examine the feasibility of mining these deposits.

Researchers recently tested a plan to control global warming in the waters of the Pacific Ocean. An international team of oceanographers reportedly found that adding large amounts of iron sulphate to the ocean would stimulate algae growth in the water, which would then absorb significant quantities of carbon dioxide from the air into the ocean. Carbon dioxide is considered to be one of the chief atmospheric gases that lead to the phenomenon of global warming.


  • Also known as: Tikhiy Okean
  • Total area: 166 million square kilometres, 64 million square miles
  • Maximum depth: 10,924 metres, 35,840 feet
  • Average depth: 4,280 metres, 14,040 feet
  • Number of islands: 30,000

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