Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceans. At about 64 million square miles (165 million square kilometers), it covers more of the Earth's surface than all the dry land put together. The navigator Ferdinand Magellan gave the ocean the name of El Mar pacifico—the peaceful sea.
The Pacific Ocean touches all the Earth's continents except Europe. The coasts of North America and South America lie as many as 12,000 miles (19,300 kilometers) to the east of the coasts of Asia and Australia. From north to south, the Pacific extends 9,600 miles (15,500 kilometers) from the narrow Bering Strait to the broad coast of Antarctica.
Under most of the Pacific Ocean lies the enormous Pacific Plate. A plate is a rigid section of the Earth's crust that moves slowly in relation to other plates. Volcanoes or earthquakes can occur where one plate meets another. The Pacific Plate meets the continental plates of North and South America as well as Southeast Asia and Oceania. Because of the many volcanoes and earthquakes that occur where these plates meet, the region is called the ring of fire.
The Pacific Plate also meets smaller plates under the ocean to form undersea ridges. The areas of deep ocean between the ridges are called basins, or plains.
The deepest parts of the ocean are not in the centers of the basins. Instead, they are usually not far from land, in areas where ocean plates are colliding with continental plates and slowly being crushed by them. These areas are called trenches. The deepest trench in the Pacific—or anywhere on Earth—is the Mariana Trench, near the Mariana Islands. At 36,201 feet (11,034 meters), it is much deeper than the Earth's highest mountain—Mount Everest—is high.
The Gulf of California is one of only a few inlets on the eastern side of the ocean. By contrast, the Asian coast is uneven and has many large seas. These include the Sea of Okhotsk, the Sea of Japan, the Yellow Sea, the East China Sea, and the South China Sea. The Bering Sea is at the ocean's northern end.
The western Pacific has many large islands. These include the island groups of Japan, the Philippines, Indonesia, and New Zealand. The smaller islands that are scattered over a large area of the central and western Pacific are divided into the Melanesian, Micronesian, and Polynesian cultural groups. The Aleutian Islands are a chain that stretches from Alaska into the North Pacific.
Most of the islands in the western Pacific are based on the Asian or Australian continental shelves, while the central islands rise from the deeper ocean floor. Hawaii is an example of a mountainous oceanic island that was born in volcanic eruptions. Many of the smaller island groups are made up of low-lying coral atolls. These islands are based on the limestone skeletons of countless coral animals, deposited together in shallow water around a sinking extinct volcano.
Water currents near the surface of the ocean tend to be driven by winds. In the North Pacific, the main current runs clockwise across the ocean, while in the South Pacific it runs counterclockwise. This means that in the extreme Northern and Southern hemispheres, most winds and currents run eastward, while near the equator they run westward. Ocean winds and currents affect climate on land. For example, the Kuroshio, or Japan Current carries warm weather north to Japan and then west to the Pacific coast of Alaska and Canada.
Heat and water vapor sometimes combine to create large circular storms with destructive winds and drenching rainfall. This type of storm—similar to a hurricane in the Atlantic Ocean—is known in the Pacific area as a typhoon. Typhoons are most common in tropical areas of the western Pacific.
Pacific Ocean currents can affect climates far from the coast through an event called El Niño. El Niño, Spanish for “the little boy,” meaning the infant Jesus, was the name Peruvian fishers gave to a warm eastward-flowing current that came every few years around Christmas. This unusual current changed the ocean environment so as to reduce their catch of fish. El Niño is now known to cause storms in California, droughts in Australia, and many other kinds of unusual weather over a wide area.
The Pacific Ocean has abundant mineral resources. Salt, bromine, and magnesium are extracted from the water. Sand, gravel, and phosphate rock are taken from the seabed. There has been underwater drilling for oil off the coasts of California and China. Large deposits of natural gas have also been found.
The ocean has a rich variety of marine life. Salmon is found near northwest North America. In addition, fishing industries in coastal countries gather large quantities of sardines, herring, hake, pollack, and shrimp. Anchovies are taken off the coast of Peru. Whaling was an important industry in the 19th century and is practiced by a few nations even now.
The Pacific Ocean contains some of the world's most important trade routes. Economic growth in Japan, South Korea, Taiwan, and other East Asian countries has led to increased shipping over the ocean, much of it directed to the United States.
The islands of the Pacific were settled by people from Southeast Asia, island by island, over a long period starting about 3,000 to 4,000 years ago. With the arrival of the Polynesian Maori people in New Zealand about 1,200 years ago, the process of settlement was just about complete.
The first known Europeans to see the Pacific Ocean were Spanish explorers led by Vasco Núñez de Balboa. Balboa saw the ocean from the Isthmus of Panama in 1513. The navigator Ferdinand Magellan entered the ocean from the south in 1520. The Spanish were followed by Dutch, French, and English explorers. After the time of Captain James Cook, who died in 1779, there were few islands of any importance that remained to be discovered by the outside world.
Scientific exploration of the Pacific in the 19th and 20th century revealed much about the ocean. While aboard the HMS Beagle in the 1830s, the English scientist Charles Darwin arrived at the modern theory of how coral islands are formed. The British Challenger Expedition (1872–76) brought back much information about depth, currents, and temperatures. In the late 1950s, a ship from the Soviet Union measured the depth of the trenches of the western Pacific. In 1960, an undersea vessel called the bathyscaphe Trieste traveled all the way to the bottom of the Mariana Trench.
Because of increasing economic activity on the ocean, some waters near the shores of big cities and ports have been polluted. Large amounts of industrial waste products, sewage, fertilizers, and pesticides have found their way into the ocean. Oil spills from ships have caused major problems in coastal areas. When the petroleum tanker Exxon Valdez ran aground off the coast of Alaska on March 24, 1989, it spilled million of gallons of crude oil, killing many animals. Overfishing by large industrial operations has greatly reduced the population of some species of fish and crustaceans as well.
