Mobility is one of the most important characteristics of the oceans. The oceans are never at rest. They are in constant motion. That is why the oceans have been described as the heartbeat of the earth.

As a matter of fact, the oceans are the bloodstream of the mother earth. Of course, there is much truth in this statement, because “the rhythmic rise and fall of the ocean waters is just like the pulsing of blood in our veins and arteries in response to the pumping of our hearts.”

There are three major types of movements in the oceans: waves, tides, and currents. Waves represent the oscillatory motions of the ocean surface induced by the force of winds. Tides are simply the rise and fall of the ocean water that can be seen along all sea coasts.

Currents are the general movement of a mass of surface water in a fairly defined direction. In other words, an ocean current may be defined as any persistent, dominantly horizontal flow of the ocean water. The ocean currents, like rivers, flow with certain velocity along a certain path.

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The ocean currents are the means of distributing both water and heat horizontally and vertically in the ocean. Waves and tides are not capable of moving water from one place to another. However, the forces responsible for creating waves and tides move around the earth, to which the waters in each place responds.

Since currents move like rivers through the oceans, are well defined and move rapidly so as to save a lot of time and fuel for the ships, in ancient days they were used as pathways. Another characteristic feature of the currents is that they exercise their influence on all parts of a body of water.

The geographers’ main interest lies in those currents which affect the surface layers of the ocean. This is so because these surface currents influence the climate, navigation, and the nature and the quantity of marine organisms.