How many layers is the ocean divided into? How many kilometers are they underwater? What are their names?

The ocean is divided into three layers: "surface water" is seawater with a water depth of more than 200 meters; "Deep water in the ocean" is seawater with a water depth of 200-700 meters; "Deep ocean water" is seawater with a water depth of less than 900 meters.

From the oceanographic theory, the compensation depth of the sea area outside the continental shelf (that is, the limit depth of photosynthesis of marine plants, which is generally considered as the limit value of 200 meters) can be called "deep sea" (no light layer).

On the other hand, seawater shallower than 200 meters is called "ocean surface" (light separation).

The average depth of the world ocean is 3800 meters. In the broad sense of oceanography, 95% of the sea water on the earth is deep ocean water. Because there is no obvious boundary between the light layer and the dark layer, there is actually a transition layer between the surface layer and the deep layer of the ocean, that is, the middle layer of the ocean.

Extended data

The water in the sea always flows in a regular and clear form, which is called ocean current. One of the most famous is the Gulf Stream, which is 50 miles wide at its narrowest point and has a velocity of 4 kilometers per hour. It goes north along the North American coast, crosses the North Atlantic, and regulates the climate in northern Europe. The North Pacific Ocean current is a similar warm current, which flows from the tropics to the north, raising the temperature on the west coast of North America.

The prevailing wind is the main force to keep the water moving. The different density of seawater is also one of the reasons for ocean currents. The density of cold water is higher than that of warm water, so cold water sinks and warm water rises. Based on the same principle, the cold water near the poles will also sink and flow to the equator below the sea surface. When it reaches the equator, the current rises, replacing the warm water flowing to the poles with surface current.

The coast and mainland of the island also have an influence on the current, either turning the current or dividing it into tributaries. However, in general, the mainstream flows around various ocean basins. Due to the influence of the earth's rotation, the current in the northern hemisphere flows clockwise, while the current in the southern hemisphere flows in the opposite direction.

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