Ocean

An ocean is a large body of water constituting a principal part of the hydrosphere (combined mass of water found on, under, and over the surface of a planet). The oceans covers 71 percent of the Earth's surface and contains 97 percent of the planet's water, yet more than 95 percent of the underwater world remains unexplored. The ocean and lakes play an integral role in many of the Earth's systems including climate and weather. The ocean supports the life of nearly 50 percent of all species on Earth and helps sustain that life providing 20 percent of the animal protein and five percent of the total protein in the human diet.

The major oceanic divisions are defined in part by the continents, various archipelagos, and other criteria. These divisions are (in descending order of size):
 * Pacific Ocean, which separates Asia and Australia from the Americas
 * Atlantic Ocean, which separates the Americas from Eurasia and Africa
 * Indian Ocean, which washes upon southern Asia and separates Africa and Australia
 * Southern Ocean (proposed) or Antarctic Ocean, sometimes considered an extension of Pacific.
 * Arctic Ocean, sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon northern North America and Eurasia.

Storage
The storehouses for the vast majority of all water on Earth are the oceans. It is estimated that of the 332,600,000 cubic miles (mi3) (1,386,000,000 cubic kilometers (km3)) of the world's water supply, about 321,000,000 mi3 (1,338,000,000 km3) is stored in oceans. That is about 96.5 percent. It is also estimated that the oceans supply about 90 percent of the evaporated water that goes into the water cycle.

Movement
There are currents and "rivers" in the oceans that move massive amounts of water around the world. These movements have a great deal of influence on the water cycle. The Kuroshio Current, off the shores of Japan, is the largest current. It can travel between 25 and 75 miles (40 and 121 kilometers) a day, 1-3 miles (1.4-4.8 kilometers) per hour, and extends some 3,300 feet (1,000 meters) deep. The Gulf Stream is a well known stream of warm water in the Atlantic Ocean, moving water from the Gulf of Mexico across the Atlantic Ocean towards Great Britain. At a speed of 60 miles (97 kilometers) per day, the Gulf stream moves 100 times as much water as all the rivers on Earth. Coming from warm climates, the Gulf Stream moves warmer water to the North Atlantic.