Mariana Trench

The ocean has a very deep spot.

It is called the Mariana Trench. It is in the Pacific Ocean. It is a long, curved place. It is the deepest part of the sea. It is deeper than a high mountain.

One part is called the Challenger Deep. Tiny living things live in the dark water. Some fish live there too.

People use special ships to visit the bottom. It is a very amazing place.

The Mariana Trench is in the western Pacific Ocean. It is the deepest part of the ocean on Earth. This trench is shaped like a crescent moon.

The deepest spot is called the Challenger Deep. It is more than 11,000 metres deep. This is much deeper than Mount Everest is tall. The water pressure at the bottom is very high. It is about 1,071.8 times the pressure at the surface.

This trench forms where two plates meet. One plate is the Pacific plate. The other is the Mariana plate. The Pacific plate is subducted, which means it is pushed under the other plate. This movement can make volcanoes and earthquakes.

Life lives in this dark place. Tiny single-celled organisms called monothalamea live there. Some fish, like the Mariana snailfish, also live in the deep. Scientists have even found plastic and candy wrappers at the bottom.

People use special ships to visit the bottom. The first crewed trip was in 1960. They used a ship called the Trieste. Since then, many people and robots have gone down to study it.

The Mariana Trench is a huge, crescent-shaped valley in the western Pacific Ocean. It is the deepest oceanic trench on our entire planet.

The deepest part is a small valley called the Challenger Deep. This spot is more than 11,000 metres below the sea surface. That is much deeper than the peak of Mount Everest is high. At this depth, the water pressure is incredibly strong. It is about 1,071.8 times the pressure we feel at sea level. This pressure is like having eight tons pressing on every square inch.

This trench forms because of how the Earth's outer shell moves. The western edge of the Pacific plate meets the smaller Mariana plate. The Pacific plate is older, cooler, and denser than the other plate. Because it is heavy, it is subducted, or pushed, beneath the Mariana plate.

As the plate sinks, it releases trapped water into the mantle. This causes melting that creates volcanic islands and earthquakes. These moving plates are part of the Izu–Bonin–Mariana subduction system. This process is what built the nearby Mariana Islands.

Humans have been trying to measure this deep place for a long time. In 1875, the Challenger expedition used a weighted rope to find the depth. Later, in 1951, the ship Challenger II used echo sounding. This was a much easier way to map the floor. In 1960, Don Walsh and Jacques Piccard made the first crewed descent. They used a special vessel called the Trieste to reach the bottom.

More recently, filmmaker James Cameron reached the bottom in 2012. In 2019, Victor Vescovo became the first person to dive into Challenger Deep more than once.

Many different types of life call this dark place home. Researchers have found tiny, single-celled organisms called monothalamea living there. Some of these are huge, growing to more than 10 centimetres. In 2014, scientists found the Mariana snailfish at a depth of 8,000 metres. This was a new record for the deepest fish seen on video. Some creatures here show deep-sea gigantism, which means they grow larger than relatives in shallow water. Even amphipods, which are small crustacean scavengers, live in the trench.

Even though it is far away, human activity reaches the trench. Scientists found plastic bags and candy wrappers at the very bottom. They also found microplastics inside the stomachs of amphipods. Some animals even have traces of chemicals like PCBs in their bodies. There is also carbon-14 from nuclear bomb testing in some aquatic animals. These findings show how everything in our world is linked together. The deep ocean is not as isolated as it seems.

The Mariana Trench is a massive, crescent-shaped oceanic trench located in the western Pacific Ocean. It sits east of the Mariana Islands and holds the title of the deepest oceanic trench on Earth.

This trench is part of a much larger geological system known as the Izu–Bonin–Mariana subduction system. This system marks the boundary where two massive tectonic plates meet and interact. Because of its extreme depth and unique environment, the trench is a vital area for scientific study. It helps researchers understand the movements of our planet's crust and the limits of life on Earth.

The formation of the trench is driven by a process called subduction. In this system, the western edge of the Pacific plate meets the smaller Mariana plate. The Pacific plate consists of some of the oldest oceanic crust on Earth, dating back up to 170 million years. Because this crust is so old, it is cooler and denser than the younger Mariana plate. This density causes the Pacific plate to be subducted, or thrust, beneath the Mariana plate.

As the plate sinks, it releases water that was trapped in its minerals. This water causes flux melting in the upper mantle. This melting process leads to the creation of earthquakes and volcanic island arcs, such as the Mariana Islands.

The topography of the trench includes several distinct features and depths. The deepest known point is located at the southern end of a small, slot-shaped valley called the Challenger Deep. The trench itself is shaped like a crescent and has specific measurements for length and width. Scientists have also identified other deep spots, such as the HMRG Deep, discovered by the Hawaii Mapping Research Group. Mapping efforts using sonar technology have even revealed four rocky outcrops that were likely once seamounts. These features show that the seafloor is complex and far from a simple, flat valley.

Humans have used many different methods to explore this deep environment throughout history. In 1875, the Challenger expedition first sounded the trench using a weighted rope. By 1951, the ship Challenger II used echo sounding, which is a more precise way to measure depth.

In 1960, Don Walsh and Jacques Piccard completed the first crewed descent using the bathyscaphe Trieste. They used iron shot for ballast and gasoline for buoyancy to manage their depth. More recently, in 2012, James Cameron reached the bottom in the Deepsea Challenger. In 2019, Victor Vescovo became the first person to dive into the Challenger Deep more than once using the DSV Limiting Factor.

The physical conditions at the bottom of the trench are extreme. At the maximum depth of approximately 11,000 metres, the water column exerts immense pressure. This pressure is about 1,071.8 times the standard atmospheric pressure at sea level, or eight tons per square inch. The temperature at these depths remains around 1 to 4 degrees Celsius.

These conditions make the trench one of the most difficult places on Earth for technology to operate. Even specialized equipment, like titanium-shelled hydrophones, must be designed specifically to withstand such massive weight.

Despite these harsh conditions, life thrives in the Mariana Trench. Researchers have discovered microbial life forms and single-celled organisms called monothalamea. Some of these monothalamea are surprisingly large, growing to more than 10 centimetres. In 2014, scientists filmed the Mariana snailfish at a depth of 8,000 metres, setting a record for the deepest fish seen on video. Some species also exhibit deep-sea gigantism, where they grow much larger than their relatives in shallower waters. These organisms, including large amphipods known as supergiants, show how life adapts to high pressure and darkness.

Human impact has reached even these remote depths through pollution. Scientists have found extremely high concentrations of PCBs, a banned chemical toxin, in crustacean scavengers. Furthermore, 100% of the amphipods studied contained at least one piece of microplastic in their stomachs. In 2019, explorers even found a plastic bag and candy wrappers at the bottom of the trench. Even carbon-14 from nuclear bomb testing has been detected in aquatic animals there. These findings connect the deep ocean to the environmental changes happening on the surface of our planet.