WHAT ARE THE OCEAN TRENCHES?

Trenches are the deepest parts of the ocean. Many trenches occur in the Pacific Ocean, especially in its western portion. Most tranches are long,narrow, and deep, 2 to 2.5 miles (3 to 4 km) below the surrounding sea floor. The greatest depth anywhere in the ocean is found in the Mariana Trench, southeast of Japan. It plunges more than 6.8 miles (11 km) below sea level. Frequent earthquakes and volcanic eruptions occur along the trenches because they are where oceanic crust is being forced underneath continental crust.

FACT FILE

For centuries, most people assumed that the cold, black depths of the ocean supported little or no life. Scientists have since discovered a great variety of living things in the deep sea.

Deep-sea fish are very different from those found in shallow waters.

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