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:''For other meanings of '''Pacific''', see [[Pacific (disambiguation)]].''
{{Five Oceans}}
The '''Pacific Ocean''' (from the [[Latin]] name ''Mare Pacificum'', "peaceful sea", bestowed upon it by the [[Portugal|Portuguese]] explorer [[Ferdinand Magellan]]) is the world's largest body of [[water]]. It encompasses a third of the [[Earth]]'s surface, having an area of [[1 E14 m²|179.7 million km²]] (69.4 million sq miles). Extending approximately [[1 E7 m|15,500 km]] (9,600 miles) from the [[Bering Sea]] in the [[Arctic]] to the icy margins of [[Antarctica]]'s [[Ross Sea]] in the south (although the Antarctic regions of the Pacific are sometimes described as part of the [[Southern Ocean]]), the Pacific reaches its greatest east-west width at about 5°N latitude, where it stretches approximately [[1 E7 m|19,800 km]] (12,300 miles) from [[Indonesia]] to the coast of [[Colombia]]. The western limit of the ocean is often placed at the [[Strait of Malacca]]. The lowest point on earth—the [[Mariana Trench]]—lies some 10,911 m (35,797 ft) below sea level.
The Pacific contains about 25,000 islands (more than the total number in the rest of the world's oceans combined), the majority of which are found south of the equator. (See: [[Pacific Islands]].)
Along the Pacific Ocean's irregular margins lie many seas, the largest of which are the [[Celebes Sea]], [[Coral Sea]], [[East China Sea]], [[Sea of Japan]], [[South China Sea]], [[Sulu Sea]], [[Tasman Sea]] and [[Yellow Sea]]. The [[Straits of Malacca]] joins the Pacific and the [[Indian ocean]]s on the west, and the [[Straits of Magellan]] links the Pacific with the [[Atlantic Ocean]] on the east.
For most of [[Ferdinand Magellan]]'s voyage from the [[Straits of Magellan]] to the [[Philippines]], the [[Portugal|Portuguese]] explorer indeed found the ocean peaceful. However, the Pacific is not always peaceful. Many [[typhoon]]s and [[hurricane]]s batter the islands of the Pacific and the lands around the Pacific rim are full of [[volcano]]es and often rocked by [[earthquake]]s. [[Tsunami]]s, caused by underwater earthquakes, have devastated many islands and wiped out whole towns.
[[Image:Pacificocean.PNG|right|Pacific Ocean]]
== Ocean bottom ==
The ocean floor of the central Pacific basin is relatively uniform, with a mean depth of about 4270 m (14,000 ft). The major irregularities in the area are the extremely steep-sided, flat-topped submarine peaks known as [[seamount]]s. The western part of the floor consists of mountain arcs that rise above the sea as island groups, such as the [[Solomon Islands]] and [[New Zealand]], and deep [[oceanic trench]]es, such as the [[Mariana Trench]], the [[Philippine Trench]], and the [[Tonga Trench]]. Most of the trenches lie adjacent to the outer margins of the wide western Pacific continental shelf.
Along the eastern margin of the [[Pacific Basin]] is the [[East Pacific Rise]], which is a part of the worldwide mid-oceanic ridge. About 3000 km (1800 miles) across, the rise stands about 3 km (2 miles) above the adjacent ocean floor.
Because a relatively small land area drains into the Pacific, and because of the ocean's immense size, most sediments are authigenic or [[Pelagic zone|pelagic]] in origin. [[Authigenic]] [[sediment]]s include [[montmorillonite]] and [[phillipsite]]. Pelagic sediments derived from seawater include pelagic red clays and the skeletal remains of sea life. Terrigenous sediments are confined to narrow marginal bands close to land.
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==Elevation extremes==
* ''lowest point:'' -10,924 m (-35,840 ft). at the bottom of the [[Mariana Trench]]
* ''highest point:'' sea level 0 m
== Water characteristics ==
Water temperatures in the Pacific vary from freezing in the poleward areas to about 29°C (84°F) near the equator. Salinity also varies latitudinally. Water near the equator is less salty than that found in the mid-latitudes because of abundant equatorial precipitation throughout the year. [[Poleward]] of the temperate latitudes salinity is also low, because little evaporation of seawater takes place in these areas.
The surface circulation of Pacific waters is generally clockwise in the [[Northern Hemisphere]] and anti-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]]. Turning eastward at about 45°N, the Kuroshio forks and some waters move northward as the [[Aleutian Current]], while the rest turn southward to rejoin the North Equatorial Current. The [[Aleutian Current]] branches as it approaches North America and forms the base of an anti-clockwise circulation in the Bering Sea. Its southern arm becomes the slow, south-flowing California Current.
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]].
== Climate ==
Only the interiors of the large land masses of [[Australia]], New Guinea, and New Zealand escape the pervasive climatic influence of the Pacific. Within the area of the Pacific, five distinctively different climatic regions exist: the mid-latitude westerlies, the trades, the monsoon region, the typhoon region, and the [[doldrums]]. Mid-latitude westerly air streams occur in both northerly and southerly latitudes, bringing marked seasonal differences in temperature. Closer to the equator, where most of the islands lie, steadily blowing trade winds allow for relatively constant temperatures throughout the year of 21-27°C (70-81°F).
The [[monsoon]] region lies in the far western Pacific between Japan and Australia. Characteristic of this climatic region are winds that blow from the continental interior to the ocean in winter and in the opposite direction in summer. Consequently, a marked seasonality of cloudiness and rainfall occurs. [[Typhoon]]s often cause extensive damage in the west and southwest Pacific. The greatest typhoon frequency exists within the triangle from southern Japan to the central Philippines to eastern Micronesia. Although more poorly defined than the other climatic regions, two major doldrum areas lie within the ocean, one located off the western shores of [[Central America]] and the other within the equatorial waters of the western Pacific. Both areas are noted for their high humidity, considerable cloudiness, light fluctuating winds, and frequent calms.
== Geology ==
The [[Andesite Line]] is the most significant regional distinction in the Pacific. It separates the deeper, basic igneous rock of the Central Pacific Basin from the partially submerged continental areas of acidic igneous rock on its margins. The Andesite Line follows the western edge of the islands off [[California]] and passes south of the [[Aleutian Islands|Aleutian arc]], along the eastern edge of the [[Kamchatka Peninsula]], the [[Kuril Islands]], Japan, the [[Mariana Islands]], the [[Solomon Islands]], and New Zealand. The dissimilarity continues northeastward along the western edge of the Albatross Cordillera along South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand—all eastward extensions of the continental blocks of Australia and Asia—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 [[Central Pacific Basin]]. It is here that 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 world's foremost belt of explosive volcanism.
== Landmasses ==
The largest landmass entirely within the Pacific Ocean is the island of [[New Guinea]] - the second largest in the world. Almost all of the smaller islands of the Pacific lie between 30°N and 30°S, extending from [[South-east Asia]] to [[Easter Island]]; the rest of the Pacific Basin is almost entirely submerged. The great triangle of [[Polynesia]], connecting [[Hawaii]], Easter Island, and [[New Zealand]], encompasses the island arcs and clusters of the Cook, [[Marquesas]], [[Samoa]], Society, [[Tokelau]], [[Tonga]], and Tuamotu islands. North of the equator and west of the [[international date line]] are the numerous small islands of [[Micronesia]], including the Caroline Islands, the Marshall Islands, and the Mariana Islands. In the southwestern corner of the Pacific lie the islands of [[Melanesia]], dominated by New Guinea. Other important island groups of [[Melanesia]] include the [[Bismarck Archipelago]], [[Fiji]], [[New Caledonia]], the [[Solomon Islands]], and [[Vanuatu]]. 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. These islands are structurally associated with the nearby continents. High islands are of volcanic origin, and many contain active volcanoes. Among these are [[Bougainville]], Hawaii, and the Solomon Islands.
The third and fourth types of islands are both the result of coralline island building. Coral reefs are low-lying structures that have built up on basaltic lava flows under the ocean's surface. One of the most dramatic is the [[Great Barrier Reef]] off northeastern Australia. 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 Island|Banaba]] (formerly Ocean Island) and [[Makatea]] in the [[Tuamotu]] group of [[French Polynesia]].
== History and economy ==
See the [[Oceania]] article for information on one set of the Pacific Island states listed below here.
Important human migrations occurred in the Pacific in prehistoric times, most notably those of [[Polynesia]]ns from [[Tahiti]] to [[Hawaii]] and [[New Zealand]]. The ocean was sighted by Europeans early in the 16th century, first by [[Vasco Núñez de Balboa]] ([[1513]]) and then by [[Ferdinand Magellan]], who crossed the Pacific during his circumnavigation ([[1519]]-[[1522]]). In [[1564]] [[conquistadors]] crossed the ocean from [[Mexico]] led by [[Miguel López de Legaspi]] who sail to the [[Philippines]] and [[Mariana Islands]]. For the remainder of the [[16th century]] [[Spain|Spanish]] influence was paramount, with ships sailing from Spain to the [[Philippines]], [[New Guinea]], and the Solomons. During the [[17th century]] the [[Netherlands|Dutch]], sailing around southern [[Africa]], dominated discovery and trade; [[Abel Janszoon Tasman]] discovered ([[1642]]) [[Tasmania]] and [[New Zealand]]. The [[18th century]] marked a burst of exploration by the [[Russia]]ns in [[Alaska]] and the [[Aleutian Islands]], the [[France|French]] in Polynesia, and the British in the three voyages of [[James Cook]] (to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest).
Growing [[imperialism]] during the [[19th century]] resulted in the occupation of much of the Pacific by the Western powers. Significant contributions to oceanographic knowledge were made by the voyages of the [[HMS Beagle|HMS ''Beagle'']] in the [[1830s]], with [[Charles Darwin]] aboard; the [[HMS Challenger|HMS ''Challenger'']] during the 1870s; the U.S.S. Tuscarora (1873-76); and the German Gazelle ([[1874]]-[[1876]]). Although the United States took the [[Philippines]] in [[1898]], [[Japan]] controlled the western Pacific by [[1914]], and occupied many other islands during World War II. By the end of that war the [[United States Navy|U.S. Pacific Fleet]] was the virtual master of the ocean.
Seventeen independent states are located in the Pacific: [[Australia]], [[Fiji]], [[Japan]], [[Kiribati]], [[Marshall Islands]], [[Micronesia]], [[Nauru]], [[New Zealand]], [[Palau]], [[Papua New Guinea]], the [[Philippines]], [[Samoa]], [[Solomon Islands]], [[Republic of China]] ([[Taiwan]]), [[Tonga]], [[Tuvalu]], and [[Vanuatu]]. Eleven of these nations have achieved full independence since 1960. The [[Northern Mariana Islands]] are self-governing with external affairs handled by the United States, and [[Cook Islands]] and [[Niue]] are in similar relationships with New Zealand. Also within the Pacific are the U.S. state of [[Hawaii]] and several island territories and possessions of [[Australia]], [[Chile]], [[Ecuador]], [[France]], [[Japan]], [[New Zealand]], the [[United Kingdom]], and the [[United States]].
The exploitation of the Pacific's mineral wealth is hampered by the ocean's great depths. In shallow waters 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. The Pacific's greatest asset is its fish. The shoreline waters of the continents and the more temperate islands yield [[herring]], [[salmon]], [[sardine]]s, [[snapper]], [[swordfish]], and [[tuna]], as well as [[shellfish]]. In 1986, the member nations of the [[South Pacific Forum]] declared the area a nuclear-free zone in an effort to halt [[nuclear testing]] and prevent the dumping of [[nuclear waste]] there.
== Bibliography ==
* Barkley, R.A., Oceanographic Atlas of the Pacific Ocean (1969)
* Cameron, I., Lost Paradise (1987)
* Couper, A., Development in the Pacific Islands (1988)
* Crump, D.J., ed., Blue Horizons (1980)
* Gilbert, John, Charting the Vast Pacific (1971)
* Lower, J. Arthur, Ocean of Destiny: A Concise History of the North Pacific, 1500-1978 (1978)
* Oliver, D.L., The Pacific Islands, 3nd ed. (1989)
* Ridgell, R., Pacific Nations and Territories, 2nd ed. (1988)
* Soule, Gardner, The Greatest Depths (1970)
* Spate, O.H., Paradise Found and Lost (1988)
* Terrell, J.E., Prehistory in the Pacific Islands (1986).
:''Based on public ___domain text from [http://oceanographer.navy.mil/pacific.html US Naval Oceanographer]''
== External links ==
* [http://www.epic.noaa.gov/epic/ewb/ EPIC Pacific Ocean Data Collection] Viewable on-line collection of observational data
* [http://www.mapsouthpacific.com/ Map South Pacific]
* [http://www.pmel.noaa.gov/tao/jsdisplay/ NOAA Ocean Surface Current Analyses - Realtime (OSCAR)] Near-realtime Pacific Ocean Surface Currents derived from satellite altimeter and scatterometer data
* [http://floats.pmel.noaa.gov/floats/ NOAA PMEL Argo profiling floats] Realtime Pacific Ocean data
* [http://www.pmel.noaa.gov/tao/jsdisplay/ NOAA TAO El Nino data] Realtime Pacific Ocean El NIno buoy data
* [http://www.southpacific.org/ South Pacific Organizer]
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[[Category:Oceans]]
[[Category:Pacific Ocean|!]]
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