ETYM French océan, Latin oceanus, Greek okeanos ocean, in Homer, the great river supposed to encompass the earth.
1. A large body of water constituting a principal part of the hydrosphere.
2. Anything apparently limitless in quantity or volume; SYN. sea.
Great mass of salt water. Strictly speaking three oceans exist —the Atlantic, Indian, and Pacific—to which the Arctic is often added. They cover approximately 70% or 363,000,000 sq km/140,000,000 sq mi of the total surface area of the Earth. Water levels recorded in the world's oceans have shown an increase of 10–15 cm/4–6 in over the past 100 years.
Depth (average) 3,660 m/12,000 ft, but shallow ledges 180 m/600 ft run out from the continents, beyond which the continental slope reaches down to the abyssal zone, the largest area, ranging from 2,000–6,000 m/6,500–19,500 ft. Only the deep-sea trenches go deeper, the deepest recorded being 11,034 m/36,201 ft (by the Vityaz, ussr) in the Mariana Trench of the W Pacific 1957.
Features deep trenches (off E and se Asia, and western South America), volcanic belts (in the W Pacific and E Indian Ocean), and ocean ridges (in the mid-Atlantic, E Pacific, and Indian Ocean).
Temperature varies on the surface with latitude (-2şC/28.4şF to +29şC/84.2şF); decreases rapidly to 370 m/1,200 ft, then more slowly to 2,200 m/7,200 ft; and hardly at all beyond that.
Water contents salinity averages about 3%; minerals commercially extracted include bromine, magnesium, potassium, salt; those potentially recoverable include aluminum, calcium, copper, gold, manganese, silver.
Pollution.
Oceans have always been used as a dumping area for human waste, but as the quantity of waste increases, and land areas for dumping it diminish, the problem is exacerbated. Today ocean pollutants include airborne emissions from land (33% by weight of total marine pollution); oil from both shipping and land-based sources; toxins from industrial, agricultural, and domestic uses; sewage; sediments from mining, forestry, and farming; plastic litter; and radioactive isotopes. Thermal pollution by cooling water from power plants or other industry is also a problem, killing coral and other temperature-sensitive sedentary species. + prikaži više

ETYM Old Eng. see, as. sae; akin to Dutch zee, os. and Old High Germ. sęo, German see, OFries. se, Dan. sö, Swed. sjö, Icel. saer, Goth. saiws, and perhaps to Latin saevus fierce, savage.
(Homonym: see).
1. A division of an ocean or a large body of salt water partially enclosed by land.
2. Turbulent water with swells of considerable size. + prikaži više