Oceans & sea

The oceans are huge masses of water between continents, but all linked together to form one mass. There are three oceans. The most easterly is the pacific ocean, covering about billion square kilometers; then comes the Atlantic, with around106 million square kilometer and Indian ocean 75 million kilometers and there are two glacier sea, the Artic and Antarctic, covering 70% of the earth’s surface, altogether. In 1951, the survey ship challenger has found the deepest part of the ocean. Echo- soundings showed part of the Mariana Trench, south of Japan, to be 10,900 meters deep. In 1960, the US navy bathyscaphe Trieste descended to the bottom of the challenger deep. The Mariana Trench is one of many deep trenches around the edges of the Pacific Ocean. These V- shaped trenches are parallel to a continent or line of islands. All water contains salt. The taste depends on the quality and the water in which it is dissolves. In the sea, the saltiness depends on the temperature, the rivers flowing into it and the currents. With high temperatures, water evaporates and the salt gets very concentrated. River brings clear water, so a sea, which has a lot of river water, has less salt than one where few rivers flow. The currents mix the waters and so dilute the quantity of salt.