Beginning of Essay
The world's ocean covers about 70% of the Earth's surface. It is use to produce us many things. It is more than a place to swimming, sailing and other recreation. serves as a source of energy, raw materials and most of all food like fish and seaweed. In this essa ....

Middle of Essay
.... (2) Thermohaline circulation. Wind-driven circulation result from the wind sets the surface waters into motion as currents. The currents generally flow horizontally-that is parallel to the earth¡¦s surface. The wind mainly affects only the upper 100 to 200 meters of water. However, the flow of wind-driven currents may extend to depths of 1,000 meters or more. Thermohaline circulation produces great vertical currents' hat flow from the surface to the ocean bottom and back. The currents largely result from differences in water temperature and salinity. The currents move sluggishly from the polar regions, along the sea floor, and back to the surface. ....