Antarctic Ocean, the ocean situated about, or within, the Antarctic Circle. The Great Southern Ocean is that part of the ocean which surrounds the world between the latitude of 40° S. and the Antarctic Circle. The northern portions of this band are often called the South Atlantic, South Indian, and South Pacific, while the southern portions are usually called the Antarctic Ocean. The average depth of the continuous ocean which surrounds south polar land is about two miles; it gradually shoals towards Antarctic land, which in some places is met with a short distance within the Antarctic Circle. Only three navigators, Cook, Weddell, and Ross, have crossed the 70th parallel south. The last in 1841 sailed along the coast as far as 70° S, within sight of high mountain ranges, which here terminated in an active volcano, Mount Erebus, 12,000 feet high. His farther progress was stopped by an icy barrier 150 to 200 feet in height, along which he sailed to the east for 300 miles. The depth off this ice-barrier was 260 fathoms, so that it Was just in the condition to generate those large, Hat-topped, tabular icebergs which are the characteristic feature of the Antarctic regions. Where the coast is steep and high, there is no true 'ice-barrier,' the ice being only 6 or 10 feet above the sea, extending many miles from the shore. Ross and D'Urville alone have succeeded in setting foot on land within the Antarctic Circle. This land was of volcanic origin; but there is no doubt a large extent of continental land around the South Pole, for the Challenger in 1874 dredged up granitites, mica-schists, sandstones, and other continental rocks close to the ice-barrier. Dr Murray estimates the extent of the Antarctic continent at 3,000,000 sq. m. Vegetation and land animals have not been observed on this land. Whales, grampuses, seals, penguins, petrels, albatrosses, and other oceanic birds abound. Diatoms are very abundant in the surface-waters, and their dead frustules form a pure white deposit called diatom ooze, about the latitude of 60°, outside the blue muds which surround the continent. Life is abundant in the surface-waters, and at the bottom of the ocean. The mean temperature both of the air and sea, south of 63° S., is even in summer below the freezing-point of sea-water. The fall of rain and snow is estimated as about equal to a rainfall of 30 inches annually. The ice on the Antarctic continent is stated by some writers to have a thickness of several miles, but there is no reliable information on this point. In 1901-4 a series of expeditions added much to our knowledge of Antarctica. See works by Mackinder (1S92), Burn-Murdoch (1894), Cook (New York, 1900), Bernacchi (1901), Borchgrevink (1901), Neumayer (Berlin, 1901), Gerlache (Paris, 1902), and Balch (Philadelphia, 1902).