The ocean encompasses a third of the Earth's surface, having an area of 179.7 million square kilometres (69.4 million sq mi and 161 million cubic mi) —significantly larger than Earth's entire landmass, with room for another Africa to spare. Extending approximately 15,500 kilometres (9,600 mi) 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 circumpolar Southern Ocean), 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 and Peru. The western limit of the ocean is often placed at the Strait of Malacca. The lowest point on earth—the Mariana Trench—lies 10,911 metres (35,797 ft) below sea level. Its average depth is 4,300 metres (14,000 ft).Important human migrations occurred in the Pacific in prehistoric times, most notably those of the Austronesians (specifically, the Polynesians) from the Asian edge of the ocean to Tahiti and then to Hawaii and New Zealand, and much later, to Easter Island.
The ocean was sighted by Europeans early in the 16th century, first by Vasco Núñez de Balboa (1513), who crossed the Isthmus of Panama, and then by Ferdinand Magellan, who sailed the Pacific during his circumnavigation (1519-1522). In 1564, conquistadors crossed the ocean from Mexico led by Miguel López de Legazpi who sailed to the Philippines and Mariana Islands. For the remainder of the 16th century, Spanish influence was paramount, with ships sailing from Spain to the Philippines, New Guinea, and the Solomon Islands; the Manila Galleons linked Manila and Acapulco. In 16th century also the Ragusean galleys of Dubrovnik led by Vice Bune explored southwestern Pacific, and discovered the islands of Bismarck Archipelago, Vanuatu (New Hebrides), etc.
During the 17th century, the Dutch, sailing around southern Africa, dominated discovery and trade; Abel Janszoon Tasman discovered Tasmania and New Zealand in 1642; in that century Ragusean traders prevailed in Melanesia. The 18th century marked a burst of exploration by the Russians in Alaska and the Aleutian Islands, the 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 Oceania by Great Britain and France, followed by the United States. Significant contributions to oceanographic knowledge were made by the voyages of the HMS Beagle in the 1830s, with Charles Darwin aboard; the HMS Challenger during the 1870s; the USS Tuscarora (1873-76); and the German Gazelle (1874-76). Although the United States conquered the Philippines in 1898, Japan controlled the western Pacific by 1914 and occupied many other islands during World War II. By the end of the war, the 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 is 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 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. The Pacific's greatest asset is its fish. The shoreline waters of the continents and the more temperate islands yield herring, salmon, sardines, 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.