sometimes called the South Sea (Fr. Ocean-Austral, Mer-du-Sud, or Grand Ocean Pacifique; Germ. Südsee, Grosser-Ocean, or Stille Meer), the largest of the great divisions of the water on the surface of the globe, stretches from the west coast of America to the east coasts of Asia and Australia, and from Behring's Strait on the N. to the Antarctic Circle on the S. It is separated from the other oceans by distinct boundaries on all sides but in the south, where it is divided from the Antarctic Ocean by the Antarctic Circle, from the Atlantic by an imaginary line drawn from Cape Horn to that circle, and from the Indian Ocean by a similar line, from South-West Cape in Tasmania to the same circle. It occupies nearly one-half of the entire surface of the earth, an area greater than that of all the dry land together; being estimated at more than 70,000,000 square miles. Its narrowest portion is in the north, where the continents of Asia and America, at Behring's Strait, approach within forty miles of each other; while further south the two continents recede to a great distance. Between the extremities of the peninsulas of Kamtschatka in Asia and Alashka in America the distance is more than 1200 miles. At the northern tropic the breadth of the ocean is about 8500 miles; at the equator it attains its greatest width, upwards of 10,000; and at the tropic of Capricorn it diminishes again to 8200 miles. The outline of the Pacific differs from that of the other great oceans in nothing more remarkably than in the absence of those great inland seas and gulfs, which in many parts of the others extend far into the heart of the continents. There are, indeed, especially along the Asiatic coasts, several portions of this ocean separated by peninsulas and chains of islands from the vast central expanse of water; but the Pacific has no inlets to be compared to the Mediterranean Sea, or Gulf of Mexico in the Atlantic, nor even to the Red Sea or Persian Gulf in the Indian Ocean. Throughout the whole of the eastern boundary of the Pacific the general character of the coast is high and bold, the lofty chains of the Andes and Rocky Mountains rising at no great distance from the sea. From Cape Horn northwards to the borders of Chili there extend a multitude of small islands, and the coast is indented by a number of bays and fiords. Farther north these islands cease, and the indentations, though numerous, are not of any size, as far as the northern extremity of South America. There the Gulf of Panama washes the inside of the curve formed by the Isthmus of Darien, 30 miles broad, which here is the only barrier between the Atlantic and Pacific oceans. Beyond this, the North American coast stretches in a north-westerly direction, without any remarkable features, as far as the long and narrow Gulf of California, the greatest of the inlets on the eastern shore of the Pacific, formed by the peninsula of the same name, which stretches southward parallel to the mainland. In the higher northern latitudes of this coast, as in the higher southern, the same features are discernible. Vancouver's Island is the most southerly of a series of islands similar to those that fringe the Patagonian coast; and in this region, as in that, the land is penetrated by numerous arms of the sea. With the peninsula of Alashka, stretching south-west from the American continent, a different character makes its appearance on the shores of the Pacific. Along the whole of the Asiatic coast there are ranges of islands, of greater or less size, which lie at a considerable distance from the land, and separate large portions of water from the rest of the ocean. The Aleutian Islands stretch westward from Alaska, and terminate not far from Kamtschatka. North of them lies that portion of the Pacific called the Sea of Behring, or Kamtschatka Sea. The peninsula of Kamtschatka projects southwards from the Asiatic mainland, and, along with the Kurile Islands, which stretch to the south-west, forms the Sea of Okhotsk. The Sea of Japan lies between the Japan Islands and the continent; and the Yellow Sea is formed by the peninsula of Corea stretching to the south. Farther south, the Chinese Sea is separated from the Pacific by the island of Formosa and the Philippines; so that there is hardly any portion of the Asiatic coast that is not more or less protected from the Pacific by a barrier of islands. South of the Philippines the ocean washes the Moluccas and the north-east coasts of Papua, communicating by many channels with the Indian Ocean. The Solomon Islands and the New Hebrides inclose between them and the Australian coast a portion of the Pacific called the Coral Sea; but the east coast of Australia has not any remarkable capes or bays. The peculiar nature of the western shores of the Pacific seems to be due in a great measure to volcanic action; since all the chains of islands from Kamtschatka to New Zealand contain either active volcanoes, or evident traces of the former existence of such.

Besides the islands already noticed lying near the shores of the ocean, the Pacific contains an immense number of others far removed from any continent. A vast extent of water, however, including the northern, eastern, and southern portions of the ocean, an area far exceeding that of the Atlantic, contains hardly any islands, the only important group being the Galapagos, which lie directly under the equator, 700 miles west of South America. In the central and western parts of the Pacific the islands are so thickly scattered, chiefly in groups, that they are sometimes considered a separate division of the globe, under the name of Polynesia. The Ladrones, Caroline, and Sandwich islands are the principal groups north of the equator; to the south, where the islands are more numerous, lie the Marquesas, Society, Navigator's, and Friendly islands, besides many others, singly and in groups. The large islands of New Zealand lie in the Southern Pacific, S.E. of Australia. Notwithstanding the vast area of the Pacific, and the extent of the coasts that it washes, but little of the river water of the world finds its way into this ocean. The great mountain range that divides the waters of the American continent is so near the shores of the Pacific, that not more than one-fifth of the area of the continent is watered by the affluents of this ocean. The only rivers of any size that enter the ocean from the east are the Rio Colorado, falling into the Gulf of California, and the Columbia River in Oregon, falling into the Pacific, to the south of Vancouver's Island. In Asia, there are three large rivers that fall into the Pacific—the Amoor, in Mongolia and Manchuria; and the Yantse-kiang and the Hoang-ho, in China; but the area watered by these, and by a few smaller streams, does not exceed one-seventh of the whole of Asia. There are no rivers of any size on the eastern coast of Australia, as the mountains that divide the waters approach there within a short distance of the sea. The Pacific, as well as the other great oceans of the world, is subject to regular winds; and these are less variable in their continuance and limits in this ocean than in the Atlantic. The N.E. trade-wind prevails throughout the ocean between the fifth and twenty-third degrees of north latitude. At different seasons, however, the northern limit varies from 20. to 27., and the southern from 1. to 11. The boundaries of the S.E. trade-wind are also different at different seasons, varying in the N. from 5. N. to 1. S. Lat., and in the S. from 20. to 25. S. Their mean extent is from the equator to 21. S. Between these two regions of the trade-winds there is a belt of about five degrees in breadth under the influence of varying winds and calms, and frequently visited by violent storms of lightning and rain. For a considerable distance from the coasts both of the American and also of the Asiatic and Australian mainlands the influence of the trade-winds is not felt, and the breezes in these parts are very irregular. The currents of the Pacific have not the same velocity or regularity as those of the Atlantic. There are, however, several worthy of notice, though comparatively little has been ascertained respecting them. South of the 33d or 34th degree of south latitude, a strong current flows from the S.W., with a velocity varying from 10 to 35 miles a day. Meeting the South American continent near the island of Chiloé, this stream divides into two parts, the one running round Cape Horn into the Atlantic, and the other, called the Peruvian current, flowing northwards along the coasts of Chili and Peru. This great body of cold water exercises a cooling influence on the climate of Peru, and extends as far north as Cape Blanco, where it turns to the west, and joins the great equatorial current moving from east to west in the southern region of the trade-winds. A south-western branch of this current washes the shores of Australia, and circles round between it and New Zealand. The region of the variable winds and calms is occupied by a current flowing from west to east; and the northern region of trade-winds, like the southern, has one which flows in an opposite direction. The latter, after being turned towards the north by the Philippine Islands, washes the coasts of Japan, and flows partly northward through Behring's Strait, and partly eastward to America, whence it circles round on its former course. The calm portions of the ocean in the centre of the revolving current in the North Pacific, and of the smaller one between Australia and New Zealand, form the principal whaling grounds in the Pacific. The tides of the Pacific are of small size. The Pacific Ocean was discovered in 1513 by Vasco Nuñez de Balboa, the Spanish governor of Darien, who crossed the isthmus, and obtained a view of this vast ocean. In 1521 Magellan entered it by rounding Cape Horn, and gave it the name of Pacific, on account of the calm weather he enjoyed after entering it, in contrast with the storms he had previously met with. This name, though not very appropriate, has continued to be that by which the ocean is most generally known. This vast expanse of water is not only very favourable to the commerce of the countries adjacent to it, but, by its productive fisheries, and its numberless islands, rich in many kinds of produce, adds in no small degree to the wealth of the world, and contributes to the necessities and to the luxuries of mankind.