Mariana Trench

The Mariana Trench is the deepest part of the ocean on Earth. It is found in the western Pacific Ocean, about 200 kilometres east of the Mariana Islands. This huge trench is shaped like a crescent wrench and stretches for about 2,550 kilometres. Its deepest point, called the Challenger Deep, is more than 11,000 metres below the surface—deeper than Mount Everest is tall!

At such amazing depths, the water puts out a huge amount of pressure—about 1,000 times more than what we feel right here on land! Even though it is very cold at the bottom, only about 1 to 4 °C, scientists have found tiny living things living there. These include special single-celled creatures called monothalamea and tiny microbial life forms that manage to survive in this extreme world.

In 2009, the United States protected part of the trench by creating the Mariana Trench Marine National Monument. This helps keep this amazing place safe for future exploration and study.

Etymology

The Mariana Trench gets its name from the nearby Mariana Islands. These islands are called Las Marianas to honor Spanish Queen Mariana of Austria. The islands are part of a chain formed on a moving plate, known as the Mariana plate, which sits on the western side of the trench.

Geology

The Mariana Trench is part of the Izu–Bonin–Mariana subduction system. This system marks the place where two large pieces of Earth's surface, called tectonic plates, meet. One plate, the Pacific plate, moves under another smaller plate, the Mariana plate. This process creates deep valleys in the ocean floor.

The movement of these plates also helps create the Mariana Islands. These islands form when melted rock from deep inside the Earth rises to the surface because of water released from the moving plates.

Research history

See also: Challenger Deep

The Mariana Trench was first explored in 1875 during the Challenger expedition. They used a weighted rope and found it to be very deep. Later, better tools helped scientists measure the depth more accurately.

In 1951, a team led by Thomas Gaskell used echo sounding to find the deepest part of the trench, called the Challenger Deep. Other scientists have continued to study and measure the trench using advanced tools. In 1995, a remote vehicle named KAIKO reached the bottom and recorded the depth.

Between 1997 and 2001, scientists found another very deep spot in the trench, naming it the HMRG Deep. In 2009, mapping tools helped create detailed maps of the trench’s shape and depth.

In 2012, researchers used special equipment to study the area under the trench, looking at structures deep below the surface.

As of 2022, 22 people and seven uncrewed vehicles have reached the bottom of the Mariana Trench. The first successful dive was in 1960 by Don Walsh and Jacques Piccard in the bathyscaphe Trieste. Since then, others have made dives, including James Cameron in 2012 and Victor Vescovo in 2019, who set a new record depth.

In 2015, scientists placed a special listening device in the trench to record sounds from the deep sea. In 2019, an underwater vehicle named Vityaz-D made an autonomous dive to the trench’s bottom. In 2020, a Chinese submersible named Fendouzhe also reached the deepest part of the trench.

Life

Scientists have discovered many surprising creatures living deep in the Mariana Trench, even though the pressure there is very high. During an expedition in 1960, they thought they saw a small flatfish and some shrimp on the trench floor. Later, tiny organisms were found in mud samples taken from the seabed. In 2011, researchers used special cameras to explore the area and found huge single-celled organisms, some larger than 10 cm.

In 2014, a new type of snailfish was found living very deep, breaking the record for the deepest fish ever seen on video. Scientists also filmed large amphipods, which grow much bigger than their relatives in shallower water. This is called deep-sea gigantism.

Pollution

In 2016, scientists studied small sea animals from the trench and found harmful chemicals called PCBs in their bodies. They also discovered that these animals had tiny pieces of plastic inside them. In 2019, a plastic bag and candy wrappers were found at the very bottom of the trench. Scientists also found traces of carbon-14, a substance from old nuclear tests, in sea animals from the trench.

Possible nuclear waste disposal site

The Mariana Trench has been suggested as a place to put away nuclear waste. Some think that the movement of Earth's plates might push the waste deep into the Earth. However, dumping nuclear waste in the ocean is not allowed by international law. Also, these areas can experience very large earthquakes, making it unsafe for storing nuclear waste.