Only the interiors of the large land masses of Australia, New Guinea, and New Zealand escape the pervasive climatic influence of the Pacific. Within the area of the Pacific, five distinctively different climatic regions exist: the mid-latitude westerlies, the trades, the monsoon region, the typhoon region, and the doldrums.

Mid-latitude westerly air streams occur in both northerly and southerly latitudes, bringing marked seasonal differences in temperature.

Closer to the equator, where most of the islands lie, steadily blowing trade winds allow for relatively constant temperatures throughout the year of 21-27°C (70-81°F).

The monsoon region lies in the far western Pacific between Japan and Australia. Characteristic of this climatic region are winds that blow from the continental interior to the ocean in winter and in the opposite direction in summer. Consequently, a marked seasonality of cloudiness and rainfall occurs. Typhoons often cause extensive damage in the west and southwest Pacific. The greatest typhoon frequency exists within the triangle from southern Japan to the central Philippines to eastern Micronesia.

Although more poorly defined than the other climatic regions, two major doldrum areas lie within the ocean, one located off the western shores of Central America and the other within the equatorial waters of the western Pacific. Both areas are noted for their high humidity, considerable cloudiness, light fluctuating winds, and frequent calms.
The Andesite Line is the most significant regional distinction in the Pacific. It separates the deeper, basic igneous rock of the Central Pacific Basin from the partially submerged continental areas of acidic igneous rock on its margins. The Andesite Line follows the western edge of the islands off California and passes south of the Aleutian arc, along the eastern edge of the Kamchatka Peninsula, the Kuril Islands, Japan, the Mariana Islands, the Solomon Islands, and New Zealand. The dissimilarity continues northeastward along the western edge of the Albatross Cordillera along South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand—all eastward extensions of the continental blocks of Australia and Asia—lie outside the Andesite Line.

Within the closed loop of the Andesite Line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Central Pacific Basin. It is here that basaltic lavas gently flow out of rifts to build huge dome-shaped volcanic mountains whose eroded summits form island arcs, chains, and clusters. Outside the Andesite Line, volcanism is of the explosive type, and the Pacific Ring of Fire is the world's foremost belt of explosive volcanism.
The largest landmass entirely within the Pacific Ocean is the island of New Guinea— the second largest in the world. Almost all of the smaller islands of the Pacific lie between 30°N and 30°S, extending from South-east Asia to Easter Island; the rest of the Pacific Basin is almost entirely submerged. The great triangle of Polynesia, connecting Hawaii, Easter Island, and New Zealand, encompasses the island arcs and clusters of the Cook, Marquesas, Samoa, Society, Tokelau, Tonga, and Tuamotu islands. North of the equator and west of the international date line are the numerous small islands of Micronesia, including the Caroline Islands, the Marshall Islands, and the Mariana Islands. In the southwestern corner of the Pacific lie the islands of Melanesia, dominated by New Guinea. Other important island groups of Melanesia include the Bismarck Archipelago, Fiji, New Caledonia, the Solomon Islands, and Vanuatu. Islands in the Pacific Ocean are of four basic types: continental islands, high islands, coral reefs, and uplifted coral platforms. Continental islands lie outside the Andesite Line and include New Guinea, the islands of New Zealand, and the Philippines. These islands are structurally associated with the nearby continents. High islands are of volcanic origin, and many contain active volcanoes. Among these are Bougainville, Hawaii, and the Solomon Islands.

The third and fourth types of islands are both the result of coralline island building. Coral reefs are low-lying structures that have built up on basaltic lava flows under the ocean's surface. One of the most dramatic is the Great Barrier Reef off northeastern Australia. A second island type formed of coral is the uplifted coral platform, which is usually slightly larger than the low coral islands. Examples include Banaba (formerly Ocean Island) and Makatea in the Tuamotu group of French Polynesia.

History and economy
See the Oceania article for information on one set of the Pacific Island states listed below here.

Important human migrations occurred in the Pacific in prehistoric times, most notably those of Polynesians from Tahiti to Hawaii and New Zealand. The ocean was sighted by Europeans early in the 16th century, first by Vasco Núñez de Balboa (1513) and then by Ferdinand Magellan, who crossed 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 Solomons. The Manila Galleons linked Manila and Acapulco. During the 17th century the Dutch, sailing around southern Africa, dominated discovery and trade; Abel Janszoon Tasman discovered (1642) Tasmania and New Zealand. 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