The Pacific separates Asia and Australia from the Americas. It may be further subdivided by the equator into northern (North Pacific) and southern (South Pacific) portions. It extends from the Antarctic region in the South to the Arctic in the north.[1] The Pacific Ocean encompasses approximately one-third of the Earths surface, having an area of 165.2 million square kilometres (63.8 million square miles) —significantly larger than Earths entire landmass of some 150 million square kilometres (58 million square miles).[13] Extending approximately 15,500 kilometres (9,600 mi) from the Bering Sea in the Arctic to the northern extent of the circumpolar Southern Ocean at 60°S (older definitions extend it to Antarcticas Ross Sea), the Pacific reaches its greatest east-west width at about 5°N latitude, where it stretches approximately 19,800 kilometres (12,300 mi) from Indonesia to the coast of Colombia – halfway across the world, and more than five times the diameter of the Moon.[14] The lowest known point on Earth—the Mariana Trench—lies 10,911 metres (35,797 ft or 5,966 fathoms) below sea level. Its average depth is 4,280 metres (14,040 ft or 2,333 fathoms).[1] Due to the effects of plate tectonics, the Pacific Ocean is currently shrinking by roughly an inch per year (2–3 cm/yr) on three sides, roughly averaging 0.2 square miles (0.52 km2) a year. By contrast, the Atlantic Ocean is increasing in size.[15][16] Along the Pacific Oceans irregular western margins lie many seas, the largest of which are the Celebes Sea, Coral Sea, East China Sea, Philippine Sea, Sea of Japan, South China Sea, Sulu Sea, Tasman Sea, and Yellow Sea. The Strait of Malacca joins the Pacific and the Indian Oceans on the west, and Drake Passage and the Strait of Magellan link the Pacific with the Atlantic Ocean on the east. To the north, the Bering Strait connects the Pacific with the Arctic Ocean.[17] Storm in Pacifica, California As the Pacific straddles the 180th meridian, the West Pacific (or western Pacific, near Asia) is in the Eastern Hemisphere, while the East Pacific (or eastern Pacific, near the Americas) is in the Western Hemisphere.[18] For most of Magellans voyage from the Strait of Magellan to the Philippines, the explorer indeed found the ocean peaceful. However, the Pacific is not always peaceful. Many tropical storms batter the islands of the Pacific.[19] The lands around the Pacific Rim are full of volcanoes and often affected by earthquakes.[20] Tsunamis, caused by underwater earthquakes, have devastated many islands and in some cases destroyed entire towns.[21] Bordering countries and territories Sovereign nations Australia Brunei Cambodia Canada Chile China Colombia Costa Rica Ecuador El Salvador Federated States of Micronesia Fiji Guatemala Honduras Indonesia Japan Kiribati North Korea South Korea Malaysia Marshall Islands Mexico Nauru New Zealand Nicaragua Palau Panama Papua New Guinea Peru Philippines Russia Samoa Singapore Solomon Islands Taiwan1 Thailand Timor-Leste Tonga Tuvalu United States Vanuatu Vietnam 1 The status of Taiwan is disputed. For more information, see political status of Taiwan. Territories American Samoa (US) United States Baker Island (US) Cook Islands (New Zealand) Australia Coral Sea Islands (Australia) Easter Island (Chile) French Polynesia (France) Guam (US) Hong Kong (China) United States Howland Island (US) United States Jarvis Island (US) United States Johnston Island (US) United States Kingman Reef (US) Macau (China) United States Midway Atoll (US) New Caledonia (France) Niue (New Zealand) Norfolk Island (Australia) Northern Mariana Islands (US) United States Palmyra Atoll (US) Pitcairn Islands (UK) Tokelau (New Zealand) Wallis and Futuna (France) United States Wake Island (US) Landmasses and islands Micronesia, Melanesia and Polynesia Tahuna maru islet, French Polynesia. The islands entirely within the Pacific Ocean can be divided into three main groups known as Micronesia, Melanesia and Polynesia. Micronesia, which lies north of the equator and west of the International Date Line, includes the Mariana Islands in the northwest, the Caroline Islands in the centre, the Marshall Islands to the west and the islands of Kiribati in the southwest.[22][23] Melanesia, to the southwest, includes New Guinea, the worlds second largest island after Greenland and by far the largest of the Pacific islands. The other main Melanesian groups from north to south are the Bismarck Archipelago, the Solomon Islands, Santa Cruz, Vanuatu, Fiji and New Caledonia.[24] The largest area, Polynesia, stretching from Hawaii in the north to New Zealand in the south, also encompasses Tuvalu, Tokelau, Samoa, Tonga and the Kermadec Islands to the west, the Cook Islands, Society Islands and Austral Islands in the center, and the Marquesas Islands, Tuamotu, Mangareva Islands and Easter Island to the east.[25] Curiñanco in the coast of Southern Chile. Islands in the Pacific Ocean are of four basic types: continental islands, high islands, coral reefs, and uplifted coral platforms. Continental islands lie outside the andesite line and include New Guinea, the islands of New Zealand, and the Philippines. Some of these islands are structurally associated with nearby continents. High islands are of volcanic origin, and many contain active volcanoes. Among these are Bougainville, Hawaii, and the Solomon Islands.[26] The Coral reefs of the South Pacific are low-lying structures that have built up on basaltic lava flows under the oceans surface. One of the most dramatic is the Great Barrier Reef off northeastern Australia with chains of reef patches. A second island type formed of coral is the uplifted coral platform, which is usually slightly larger than the low coral islands. Examples include Banaba (formerly Ocean Island) and Makatea in the Tuamotu group of French Polynesia.[27][28] Water characteristics Sunset in Monterey County, California, U.S. The volume of the Pacific Ocean, representing about 50.1 percent of the worlds oceanic water, has been estimated at some 714 million cubic kilometers.[29] Surface water temperatures in the Pacific can vary from −1.4 °C (29.5 °F), the freezing point of sea water, in the poleward areas to about 30 °C (86 °F) near the equator.[30] Salinity also varies latitudinally reaching a maximum of 37 parts per thousand in the southeastern area. The water near the equator, which can have a salinity as low as 34 parts per thousand, is less salty than that found in the mid-latitudes because of abundant equatorial precipitation throughout the year. The lowest counts of less than 32 parts per thousand are found in the far north as less evaporation of seawater takes place in these frigid areas.[31] The motion of Pacific waters is generally clockwise in the Northern Hemisphere (the North Pacific gyre) and counter-clockwise in the Southern Hemisphere. The North Equatorial Current, driven westward along latitude 15°N by the trade winds, turns north near the Philippines to become the warm Japan or Kuroshio Current.[32] Turning eastward at about 45°N, the Kuroshio forks and some water moves northward as the Aleutian Current, while the rest turns southward to rejoin the North Equatorial Current.[33] The Aleutian Current branches as it approaches North America and forms the base of a counter-clockwise circulation in the Bering Sea. Its southern arm becomes the chilled slow, south-flowing California Current.[34] The South Equatorial Current, flowing west along the equator, swings southward east of New Guinea, turns east at about 50°S, and joins the main westerly circulation of the Southern Pacific, which includes the Earth-circling Antarctic Circumpolar Current. As it approaches the Chilean coast, the South Equatorial Current divides; one branch flows around Cape Horn and the other turns north to form the Peru or Humboldt Current.[35] Climate The weather systems in the Northern and Southern hemispheres generally mirror each other. The trade winds in the southern and eastern Pacific are remarkably steady while conditions in the North Pacific are far more varied with, for example, cold winter temperatures on the east coast of Russia contrasting with the milder weather off British Columbia during the winter months.[36] Cyclones are liable to form south of Mexico, striking Central America between June and October, as well as in southeast and east Asia from May to December, especially in August and September. In the western Pacific, monsoons in the summer months contrast with dry winds in the winter which blow over the ocean from the Asian landmass. In the equatorial Pacific, El Niño, a band of warm ocean temperatures, affects weather conditions in the western Pacific. In the far north, icing from October to May can present a hazard for shipping while persistent fog occurs from June to December.[37] Geology Main articles: Geology of the Pacific Ocean and Pacific Plate The Pacific is ringed by many volcanoes and oceanic trenches Ulawun stratovolcano situated on the island of New Britain, Papua New Guinea The ocean was mapped by Abraham Ortelius; he called it Maris Pacifici because of Ferdinand Magellan, who sailed the Pacific during his circumnavigation from 1519 to 1522 and said that it was much more calm than the Atlantic.[38] The andesite line is the most significant regional distinction in the Pacific. A petrologic boundary, separates the deeper, mafic igneous rock of the Central Pacific Basin from the partially submerged continental areas of felsic igneous rock on its margins.[39] The andesite line follows the western edge of the islands off California and passes south of the Aleutian arc, along the eastern edge of the Kamchatka Peninsula, the Kuril Islands, Japan, the Mariana Islands, the Solomon Islands, and New Zealands North Island.[23][40] The dissimilarity continues northeastward along the western edge of the Andes Cordillera along South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand lie outside the andesite line. Within the closed loop of the andesite line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Pacific basin. Here basaltic lavas gently flow out of rifts to build huge dome-shaped volcanic mountains whose eroded summits form island arcs, chains, and clusters. Outside the andesite line, volcanism is of the explosive type, and the Pacific Ring of Fire is the worlds foremost belt of explosive volcanism.[22] The Ring of Fire is named after the several hundred active volcanoes that sit above the various subduction zones. The Pacific Ocean is the only ocean which is almost totally bounded by subduction zones. Only the Antarctic and Australian coasts have no nearby subduction zones. Geological history The Pacific Ocean developed from the Panthalassa following the breakup of Pangaea. There is no firm date for when the changeover occurred, as the replacement of the sea bed is a continuous process, though reconstruction maps often change the name from Panthalassic to Pacific around the time the Atlantic Ocean began to open.[41] The Panthalassic Ocean first opened 750 million years ago at the breakup of Rodinia,[41] but the oldest Pacific Ocean floor is only around 180 Ma old.[42] Seamount chains The Pacific Ocean contains several long seamount chains, formed by hotspot volcanism. These include the Hawaiian–Emperor seamount chain and the Louisville seamount chain. Economy The exploitation of the Pacifics mineral wealth is hampered by the oceans great depths. In shallow waters of the continental shelves off the coasts of Australia and New Zealand, petroleum and natural gas are extracted, and pearls are harvested along the coasts of Australia, Japan, Papua New Guinea, Nicaragua, Panama, and the Philippines, although in sharply declining volume in some cases.[43] Fishing Fish are an important economic asset in the Pacific. The shallower shoreline waters of the continents and the more temperate islands yield herring, salmon, sardines, snapper, swordfish, and tuna, as well as shellfish.[44] Overfishing has become a serious problem in some areas. For example, catches in the rich fishing grounds of the Okhotsk Sea off the Russian coast have been reduced by at least half since the 1990s as a result of overfishing.[45] Environmental issues Marine debris on a Hawaiian coast Main article: Marine pollution See also: Great Pacific Garbage Patch and Ship pollution The quantity of small plastic fragments floating in the north-east Pacific Ocean has increased a hundredfold over the past 40 years (2012).[46] Marine pollution is a generic term for the harmful entry into the ocean of chemicals or particles. The main culprits are those using the rivers for disposing of their waste.[47] The rivers then empty into the Ocean, often also bringing chemicals used as fertilizers in agriculture. The excess of oxygen-depleting chemicals in the water leads to hypoxia and the creation of a dead zone.[48] Marine debris, also known as marine litter, is human-created waste that has ended up floating in a lake, sea, ocean or waterway. Oceanic debris tends to accumulate at the centre of gyres and coastlines, frequently washing aground where it is known as beach litter.[47] In addition, the Pacific Ocean has served as the crash site of satellites, including Mars 96, Fobos-Grunt and Upper Atmosphere Research Satellite. Major ports and harbors Main article: List of ports and harbors of the Pacific Ocean See also Portal icon Environment portal Portal icon Ecology portal Portal icon Geography portal Portal icon Weather portal Asia-Pacific Economic Cooperation Pacific-Antarctic Ridge Pacific coast Pacific hurricane Pacific Time Zone Pacific War Seven Seas Typhoon War of the Pacific References ^ Jump up to: a b c Pacific Ocean. Britannica Concise. 2006. Chicago: Encyclopædia Britannica, Inc. Jump up ^ International Hydrographic Organization (1953). Limits of Oceans and Seas, 3rd edition. Monte Carlo, Monaco: International Hydrographic Organization. Retrieved 12 June 2010. Jump up ^ Japan Atlas: Japan Marine Science and Technology Center. Retrieved 2007-07-04. Jump up ^ CATHOLIC ENCYCLOPEDIA: Ferdinand Magellan. Newadvent.org. 1910-10-01. Retrieved 31 October 2010. Jump up ^ Library Acquires Copy of 1507 Waldseemüller World Map - News Releases (Library of Congress). Loc.gov. Retrieved 2013-04-20. Jump up ^ Stanley, David (2004). South Pacific. David Stanley. p. 19. ISBN 978-1-56691-411-6. Retrieved 12 June 2013. Jump up ^ Ober, Frederick Albion. Vasco Nuñez de Balboa. Library of Alexandria. p. 129. ISBN 978-1-4655-7034-5. Retrieved 12 June 2013. Jump up ^ Life in the sea: Pacific Ocean, Oceanário de Lisboa. Retrieved 9 June 2013. Jump up ^ Henderson, James D.; Delpar, Helen; Brungardt, Maurice Philip; Weldon, Richard N. (January 2000). A Reference Guide to Latin American History. M.E. Sharpe. p. 28. ISBN 978-1-56324-744-6. Retrieved 12 June 2013. Jump up ^ Primary Australian History: Book F [B6] Ages 10-11. R.I.C. Publications. 2008. p. 6. ISBN 978-1-74126-688-7. Retrieved 12 June 2013. Jump up ^ Williams, Glyndwr (2004). Captain Cook: Explorations And Reassessments. Boydell Press. p. 143. ISBN 978-1-84383-100-6. Retrieved 12 June 2013. Jump up ^ Tewari, Nita; Alvarez, Alvin N. (17 September 2008). Asian American Psychology: Current Perspectives. CRC Press. p. 161. ISBN 978-1-84169-749-9. Retrieved 12 June 2013. Jump up ^ Area of Earths Land Surface, The Physics Factbook. Retrieved 9 June 2013. Jump up ^ Nuttall, Mark (2005). Encyclopedia of the Arctic: A-F. Routledge. p. 1461. ISBN 978-1-57958-436-8. Retrieved 10 June 2013. Jump up ^ Plate Tectonics, Bucknell University. Retrieved 9 June 2013. Jump up ^ Young, Greg (2009). Plate Tectonics. Capstone. pp. 9–. ISBN 978-0-7565-4232-0. Retrieved 9 June 2013. Jump up ^ International Hydrographic Organization (1953). Limits of Oceans and Seas. International Hydrographic Organization. Retrieved 9 June 2013. Jump up ^ Agno, Lydia (1998). Basic Geography. Goodwill Trading Co., Inc. pp. 25–. ISBN 978-971-11-0165-7. Retrieved 9 June 2013. Jump up ^ Pacific Ocean: The trade winds, Encyclopædia Britannica. Retrieved 9 June 2013. Jump up ^ Murphy, Shirley Rousseau (1979). The Ring of Fire. Avon. ISBN 978-0-380-47191-1. Retrieved 9 June 2013. Jump up ^ Bryant, Edward (2008). Tsunami: The Underrated Hazard. Springer. pp. 26–. ISBN 978-3-540-74274-6. Retrieved 9 June 2013. ^ Jump up to: a b Academic American encyclopedia. Grolier Incorporated. 1997. p. 8. ISBN 978-0-7172-2068-7. Retrieved 12 June 2013. ^ Jump up to: a b Lal, Brij Vilash; Fortune, Kate (2000). The Pacific Islands: An Encyclopedia. University of Hawaii Press. pp. 63–. ISBN 978-0-8248-2265-1. Retrieved 14 June 2013. Jump up ^ West, Barbara A. (2009). Encyclopedia of the Peoples of Asia and Oceania. Infobase Publishing. pp. 521–. ISBN 978-1-4381-1913-7. Retrieved 14 June 2013. Jump up ^ Dunford, Betty; Ridgell, Reilly (1996). Pacific Neighbors: The Islands of Micronesia, Melanesia, and Polynesia. Bess Press. pp. 125–. ISBN 978-1-57306-022-6. Retrieved 14 June 2013. Jump up ^ Gillespie, Rosemary G.; Clague, David A. (2009). Encyclopedia of Islands. University of California Press. p. 706. ISBN 978-0-520-25649-1. Retrieved 12 June 2013. Jump up ^ Coral island, Encyclopædia Britannica. Retrieved 22 June 2013. Jump up ^ Nauru, Charting the Pacific. Retrieved 22 June 2013. Jump up ^ PWLF.org - The Pacific WildLife Foundation - The Pacific Ocean. Retrieved 23 August 2013. Jump up ^ Mongillo, John F. (2000). Encyclopedia of Environmental Science. University Rochester Press. pp. 255–. ISBN 978-1-57356-147-1. Retrieved 9 June 2013. Jump up ^ Pacific Ocean: Salinity, Encyclopædia Britannica. Retrieved 9 June 2013. Jump up ^ Wind Driven Surface Currents: Equatorial Currents Background, Ocean Motion. Retrieved 9 June 2013. Jump up ^ Kuroshio, Encyclopædia Britannica. Retrieved 9 June 2013. Jump up ^ Aleutian Current, Encyclopædia Britannica. Retrieved 9 June 2013. Jump up ^ South Equatorial Current, Encyclopædia Britannica. Retrieved 9 June 2013. Jump up ^ Pacific Ocean: Islands, Encyclopædia Britannica. Retrieved 13 June 2013. Jump up ^ Pacific Ocean, World Factbook, CIA. Retrieved 13 June 2013. Jump up ^ Turnbull, Alexander (15 December 2006). Map New Zealand: 100 Magnificent Maps from the Collection of the Alexander Turnbull Library. Godwit. p. 8. ISBN 978-1-86962-126-1. Retrieved 10 June 2013. Jump up ^ Trent, D. D.; Hazlett, Richard; Bierman, Paul (2010). Geology and the Environment. Cengage Learning. p. 133. ISBN 978-0-538-73755-5. Retrieved 10 June 2013. Jump up ^ Mueller-Dombois, Dieter (1998). Vegetation of the Tropical Pacific Islands. Springer. p. 13. ISBN 978-0-387-98313-4. Retrieved 10 June 2013. ^ Jump up to: a b GEOL 102 The Proterozoic Eon II: Rodinia and Pannotia. Geol.umd.edu. 2010-01-05. Retrieved 31 October 2010. Jump up ^ Mussett, Alan E.; Khan, M. Aftab (23 October 2000). Looking Into the Earth: An Introduction to Geological Geophysics. Cambridge University Press. p. 332. ISBN 978-0-521-78574-7. Retrieved 10 June 2013. Jump up ^ Pacific Ocean: Fisheries, Encyclopædia Britannica. Retrieved 12 June 2013. Jump up ^ Pacific Ocean: Commerce and Shipping, The Columbia Electronic Encyclopedia, 6th edition. Retrieved 14 June 2013. Jump up ^ Pacific Ocean Threats & Impacts: Overfishing and Exploitation, Center for Ocean Solutions. Retrieved 14 June 2013. Jump up ^ Plastic waste in the North Pacific is an ongoing concern BBC 9 May 2012 ^ Jump up to: a b PHOTOS: Giant Ocean-Trash Vortex Documented-A First. News.nationalgeographic. Retrieved 31 October 2010. Jump up ^ Gerlach: Marine Pollution, Springer, Berlin (1975) Further reading Barkley, Richard A. (1968). Oceanographic Atlas of the Pacific Ocean. Honolulu: University of Hawaii Press. prepared by the Special Publications Division, National Geographic Society. (1985). Blue Horizons: Paradise Isles of the Pacific. Washington, D.C.: National Geographic Society. ISBN 0-87044-544-8. Cameron, Ian (1987). Lost Paradise: The Exploration of the Pacific. Topsfield, Mass.: Salem House. ISBN 0-88162-275-3. Couper, A. D. (ed.) (1989). Development and Social Change in the Pacific Islands. London: Routledge. ISBN 0-415-00917-0. Gilbert, John (1971). Charting the Vast Pacific. London: Aldus. ISBN 0-490-00226-9. Igler, David (2013). The Great Ocean: Pacific Worlds from Captain Cook to the Gold Rush. New York: Oxford University Press. ISBN 0-199-91495-8. Lower, J. Arthur (1978). Ocean of Destiny: A Concise History of the North Pacific, 1500-1978. Vancouver: University of British Columbia Press. ISBN 0-7748-0101-8. Napier, W.; Gilbert, J., and Holland, J. (1973). Pacific Voyages. Garden City, N.Y.: Doubleday. ISBN 0-385-04335-X. Nunn, Patrick D. (1998). Pacific Island Landscapes: Landscape and Geological Development of Southwest Pacific Islands, Especially Fiji, Samoa and Tonga. [email protected]. ISBN 978-982-02-0129-3. Oliver, Douglas L. (1989). The Pacific Islands (3rd ed.). Honolulu: University of Hawaii Press. ISBN 0-8248-1233-6. Ridgell, Reilly (1988). Pacific Nations and Territories: The Islands of Micronesia, Melanesia, and Polynesia (2nd ed.). Honolulu: Bess Press. ISBN 0-935848-50-9. Soule, Gardner (1970). The Greatest Depths: Probing the Seas to 20,000 feet (6,100 m) and Below. Philadelphia: Macrae Smith. ISBN 0-8255-8350-0. Spate, O. H. K. (1988). Paradise Found and Lost. Minneapolis: University of Minnesota Press. ISBN 0-8166-1715-5. Terrell, John (1986). Prehistory in the Pacific Islands: A Study of Variation in Language, Customs, and Human Biology. Cambridge: Cambridge University Press. ISBN 0-521-30604-3.
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