Neptune's Needle

The largest and deepest ocean (c.70,000,000 sq miles), occupying about one-third of the earth's surface. Named by the Spanish explorer, Ferdinand Magellan; the Southern part is also known as the South Seas.

Boundaries, Length, Width, Arms

Extends from the Arctic to Aantarctic regions between North America and South America on the east and Asia and Australia on the west. It is connected with the Arctic Ocean by the Bering Strait; with the Atlantic Ocean by the Drake Passage, Straits of Magellan, and the Panama Canal; and with the Indian Ocean by passages in the Malay Archipelago and between Australia and Antarctica. Its maximum length is c.9,000 mi/14,500 km, and its greatest width c.11,000 mi/17,700 km, between the Isthmus of Panama and the Malay Peninsula. The principal arms of the Pacific Ocean are (in the N) the Bering Sea; (in the E) the Gulf of California; (in the S) Ross Sea; and (in the W) the Sea of Okhotsk, the Sea of Japan (also called the East Sea), and the Yellow, East China, South China, Philippine, Coral, and Tasman seas.

Continental Shelves, Volcanoes, Islands

Along the E Pacific shore, generally, the coast rises abruptly from a deep sea floor to mountain heights on land, and there is a narrow continental shelf. The Asian coast is generally low and indented and is fringed with islands rising from a wide continental shelf. A series of volcanoes, the Circum-Pacific Ring of Fire, rims the deep Pacific Basin. The approximately 20,000 islands in the Pacific Ocean are concentrated in the S and W. Most of the larger islands are part of the continental structures and rise from continental shelves; their volcanoes are commonly andesitic and explosive; these include the Japanese island arc, the Malaysian Archipelago, and Melanesia. The islands of NW North America and SW South America are also continental. Dispersed within the Pacific and rising from the ocean floor are ridges which sometimes emerge as high basaltic volcanic islands (such as the Hawaiian Islands) or form the submarine bases of low coral islands (such as many in Oceania).

Depth, Swells, Ocean Currents, and Whirls

Few large rivers drain into the Pacific Ocean; the largest are the Columbia of North America and the Huang He (Yellow) and Chang Jiang (Yangtze) of China. The floor of the Pacific Ocean, which has an average depth of c.14,000 ft/4,300 m, is largely a deep sea plain. The greatest known depth (35,839 ft/10,924 m) is in the Challenger Deep in the Marianas Trench c.250 mi/400 km SW of Guam. Rising from the plain are swells (many of which are volcanic), seamounts, and guyots; the extensive Albatross Plateau (East Pacific Rise) covers most of the SE and E central Pacific Basin. Huge whirls, formed by the major ocean currents, are found roughly N and S of the equator; the Equatorial Countercurrent separates them. The N whirl is formed by the North Equatorial Current, Japan Current, North Pacific Drift, and California Current; the S whirl is formed by the South Equatorial Current, East Australian Current, West Wind Drift, and Peruvian (or Humboldt) Current. There are many branch and feeder currents that help to constantly circulate ocean water of differing temperatures and salinities.

Exploration

The Pacific islands of the S and W were populated by Asian migrants who crossed long distances of open sea in simply-constructed boats. European travelers including Marco Polo had reported an ocean off Asia, and in the late 15th century trading ships had sailed around Africa to the W rim of the Pacific, but recognition of the Pacific as distinct from the Atlantic Ocean dates from Balboa's sighting of its E shore (1513). Magellan's crossing to the Philippines (1520-1521) initiated a series of explorations, including those of Drake, Tasman, Dampier, Cook, Bering, and Vancouver, which by the end of the 18th century had disclosed the coastline and the major islands. In the 16th century supremacy in the Pacific area was shared by Spain and Portugal. The British and the Dutch established footholds in the 17th century, France and Russia in the 18th, and Germany, Japan, and the U.S. in the 19th. Sealers and whalers sailed the Pacific from the late 18th century, and Yankee clippers entered Pacific trade in the early 19th century.

Economic Activity

The principal in-shore commercial fishing areas in the Pacific are found in the shallower waters of the continental shelf; where salmon, halibut, herring, and sardines are taken, but tuna and bonito are the chief catch of the pelagic fisheries. Many of the trans-Pacific sea-lanes pass through the Hawaiian Islands; the chief Pacific ports are San Francisco, Los Angeles, Seattle, Tokyo-Yokohama, Guangzhou, Hong Kong, Shanghai, Manila, and Sydney. Since the 1950s some of the South Pacific islands have become tourist centers. The international date line passes through the Pacific Ocean.

Sources

Compiler

Peter Richards