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.
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 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.
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