The Pacific Ocean

The Pacific Ocean

The Pacific is the world’s largest and deepest ocean. It is nearly twice the area of the Atlantic and contains almost three times as much water. The ocean is dotted with islands and surrounded by some of the world’s most populous states; over half the world’s population lives on its shores. The Pacific is bordered by active plate margins known as the “Ring of Fire,” causing earthquakes and tsunamis, and creating volcanic islands and subterranean mountain chains. The largest underwater mountains break the surface as island arcs. The fisheries of the Pacific are some of the most productive in the world and provide a vital resource for many of the Pacific islands. Since the Second World War there has been a shift in trading patterns, with a considerable growth in trade between the US and the countries of the Pacific Rim.

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The Ring of Fire

The active plate margins surrounding the Pacific have created numerous land and island volcanoes along its border. The actual basin of the Pacific is made up of a number of separate tectonic plates which move away from each other, colliding with other plates. When they collide, the oceanic plates, being thinner, are forced beneath the thicker continental plates, forming deep ocean trenches and high ridges. These collision zones are known as subduction zones and are characterized by intense seismic and volcanic activity.

American Samoa and Samoa

American Samoa and Samoa are part of the island archipelago of Polynesia. The two most populous islands are Tutuila in American Samoa and ‘Upolu in Samoa. Although the economies of both these states remain predominantly resource-based, both are expanding their light manufacturing sectors, and the US administration is the primary employer in American Samoa. Tuna fishing is particularly important: 25% of all tuna consumed in the US is processed and canned in Pago Pago.

The Landscape

Although it is still the largest ocean, the basin of the Pacific has been gradually decreasing in size due to the movement of the Indo-Australian Plate. The oldest parts are about 135 million years old. The eastern border of the Pacific is characterized by a continuous mountain chain running the length of the North and South American continents. The eastern basin has a low, uninterrupted relief, at depths averaging 15,000 ft (4570 m). In contrast, the western Pacific is scattered with island arcs and bounded by a series of deep ocean trenches. An almost continuous chain of volcanoes surrounds the ocean and an active mid-ocean ridge runs northeast–southwest.


The Kingdom of Tonga lies in the southwest Pacific, about 2000 miles (3000 km) off the east coast of Australia. It comprises 169 islands of which only 36 are permanently inhabited. The majority of the population live on the largest island, Tongatapu. There are only three sizeable towns and the main commercial center is the capital Nuku‘alofa. Tonga’s economy is based mainly on agriculture; coconuts, bananas, and vanilla are grown as cash crops for export. Although there is some light manufacturing, growing land shortages have forced increased migration to New Zealand and Australia.