Mariana Trench:

The deepest point on Earth

Have you ever been to the Everest? Almost all of you will say no, but there are brave people who had reached the very top of this highest point on Earth. What if I say that you can insert Mount Everest in the Mariana Trench and there would still be some space left? Now you can just imagine the depth of the Mariana Trench.

The Mariana Trench is situated in the floor of the western Pacific Ocean, just east of the Mariana Islands. It's 1,554 miles long and 44 miles wide. The deepest end of the trench was first discovered by a British survey ship named Challenger II in 1951, and was named as the 'Challenger Deep'.

Water pressure increases with depth. So, the deepest place of the Mariana is the place with the highest pressure. Pressure from the weight of the vast ocean above is over eight tons per square inch. Now, we'll explore its geographical features. The ocean bottom is divided into three main areas; the continental shelf, the continental slope and the deep ocean basin.

The continental shelf extends under water from each of the major land masses. It is the submerged portion of the continents. The shelf has features similar to those on land, including hills, ridges and canyons. The size of the shelf varies. It may be virtually non-existent in some areas; elsewhere, it may extend from the shore to several hundred miles. The average distance of the shelf is about 64km.

It is beyond the continental shelf that the 'deep sea' begins. The shelf ends at a depth of about 200m, giving way to the steeper continental slope, which descends about 3,700m, to the deep ocean basin. At this point, the ocean floor deepens sharply and its features again resemble those on land with great plains and mountains.

Janani Amarasekara

Life inside Mariana

We mentioned about the deepest point in the trench and the water pressure at this point. Sun rays obviously won't reach this lonely place. It is a dark world out there, under the sea bed. One can compare it with hell, I guess. So, can you believe that there is actually life at the deepest end of the Earth?

Scientists once took a sample from the Challenger Deep, which is nearly seven miles deep. They were amazed to see that the soil was packed with a unique community of mostly soft-walled, single-celled organisms that are thought to resemble some of the earliest living forms.

This species was named as foraminifera. These organisms are distinct of animals, plants and fungi. There are an estimated 4,000 species of living foraminifera. They inhabit a wide range of marine environments, mostly on ocean bottoms. Scientists have discovered 432 types of foraminifera living in the Challenger Deep. Other types of living beings include algae and slim moulds. This is an example of how you can find life even in the most extreme environments.

Now that you know there's no sunlight at the bottom, you must be wondering how these creatures live without vegetation (because there can't be vegetation without sunlight). Scientists have found the answer to this question too.

The deep ocean bacteria is always a present and potential food source, nourished by a chemical synthesis of Hydrogen Sulphide (H2S - the gas that smells like rotten eggs) and other substances in the naturally heated water from the Earth core. Bacteria grows in this environment and become food for the mussels and clams. This is the food chain of the Mariana Trench.

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Bottom of the trench

The bottom is muddy like a saltwater marsh. It's a greyish, yellowish ooze. This ooze comprises particles(minute portions of matter) of sediments and dead bodies of microscopic plankton, which, year after year, fall to the bottom.

The oceanic world gives up its secrets reluctantly, and not without much effort on the part of man. There is still a great deal of research and planning to be done by those who will venture into this highly pressurised, cold world in eternal darkness.