Pacific Ocean

World's largest ocean, extending from Antarctica to the Bering Strait; area 166,242,500 sq km/64,186,500 sq mi; greatest breadth 16,000 km/9,942 mi; length 11,000 km/6,835 mi; average depth 4,188 m/13,749 ft; greatest depth of any ocean is the found in the Mariana Trench, in the northwest Pacific, with a depth of 11,034 m/36,201 ft.

Depth The Pacific is the deepest ocean; the western and northern areas are deeper than the east and south. Some of the greatest depths lie alongside islands, such as the Mariana Trench (11,034 m/36,201 ft), alongside the Mariana Islands; the Tuscarora Deep (8,500 m/27,886 ft), alongside Japan and the Kurils and extending for 640 km/397 mi; and the Aldrich Deep, east of New Zealand (9,400 m/30,840 ft).

Islands There are over 2,500 islands in the central and western regions, of volcanic or coral origin, many being atolls. The Pacific is ringed by an area of volcanic activity, with accompanying earthquakes.

Currents Winds in the northern Pacific produce generally clockwise currents; a northward current from the Equator flows past the Philippines and is joined by currents from the East Indies and China Sea at Taiwan to form the Kuroshio. This branches opposite Vancouver to flow south as the California current, and north around the Alaskan coast. A cold current from the Bering Sea enters the Okhotsk and Japan seas, causing freezing in winter. In the South Pacific the trade winds cause anticlockwise equatorial currents which branch opposite southern Chile, to flow north as the cooling Peru Current (Humboldt Current), and south round Cape Horn.

European exploration Vasco Núñez de Balboa was the first European to see the Pacific Ocean from Panama in 1513. Ferdinand Magellan sailed through the Strait of Magellan in 1520, and gave the name to the ocean (because of its calmness during his voyage). In 1577 Francis Drake, the first Englishman to enter the Pacific, sailed north to California and across to the Moluccas. The Australasian region was explored by Europeans in the 17th century.