So what is the Mariana Trench? And what exactly is living in its depths? In this article, we’ll explore everything you need to know about the Mariana Trench, including some astounding facts about this mysterious habitat and its extreme pressure. 



What is the Mariana Trench?

The Mariana Trench is the deepest oceanic trench on Earth.

It is located between Hawaii and the Philippines and is shaped like a crescent. It is named after the nearby Mariana Islands (which in turn are named after Queen Mariana of Austria) and was discovered in 1875. The depths were sounded using a weighted rope which at the time recorded a depth of 26,850 feet. Today, the depth has been confirmed at closer to 36,200 feet.

The waters around the Mariana Islands
The waters around the Mariana Islands

The deepest point of the trench is nearly 7 miles beneath the ocean’s surface. At the bottom of the trench, the ocean exerts a phenomenal amount of pressure, around 1,071 times that at sea level. In 2009, it was established as a U.S. National Monument.

Cross section of the Mariana trench
Cross section of the Mariana trench

Credit: Hussong, Fryer (1981), U.S. government supplied image, redrawn into SVG by Vanessa Ezekowitz.

The second deepest point on earth is the Horizon Deep in the Tonga Trench at 35,433 feet or 10,800 meters. 

The third deepest point is the Sirena Deep, previously known as the HMRG Deep. It too is located in the Mariana Trench and is 35,151 ft or 10,714 meters. 

Mariana Trench Information

The Mariana Trench is one of the most incredible places on Earth; check out these astounding facts about this world wonder:

  • Maximum Depth: 7 miles or 36,200 feet
  • Location: Floor of the Pacific Ocean, between Hawaii and the Philippines
  • Length: 1,500 miles long
  • Width: About 43 miles on average
  • Pressure: 1,086 bars (15,750 psi)
Location of the Mariana Trench
Location of the Mariana Trench

Credit: Fosas Marianas


Discovery and Exploration of the Mariana Trench

The Mariana Trench Marine National Monument was first sounded and acknowledged at the deepest point on Earth in 1875 during the Challenger Expedition. It is located east of the Mariana Islands, and at the time, it was believed to be 26,850 feet or 8,184 meters. More than 20 years later, another expedition on the USS Nero re-recorded the depth closer to 31,614 feet of 9.636 meters. 

Famously, a recent expedition to the bottom of the trench in 2019 resulted in discovering a plastic bag and candy wrappers. 

The Challenger Deep

The Challenger Deep, commonly known as the deepest single point on Earth, is located at the southern end of the Mariana Trench, close to the Mariana Islands from which it takes its name. It is around 35,827 feet deep, or 10,920 meters. It was named after the HMS Challenger, the first ship to sound the trench. 

In 1960, the bathyscaphe Trieste, piloted by Jacques Piccard and Don Walsh, made the first descent into the trench and were the first people to reach the bottom. The first solo manned descent was completed in 2012 by filmmaker James Cameron onboard the Deepsea Challenger during the Deepsea Challenge expedition. Since mid-2022, twenty-seven people have traveled to the bottom of the trench. 

The Trieste Submarine, two years before its descent into the Challenger Deep
The Trieste Submarine, two years before its descent into the Challenger Deep


Mariana Trench Animals

The Mariana Trench is one of the most inhospitable places on Earth. But that doesn’t mean its depths aren’t teeming with animal life. Many of these creatures evolved adaptions (like the angler fish’s light and the hatchet fish’s large eyes) to help them navigate the pitch black, freezing cold, and high-pressure waters.

Some of the many strange animals living in the Mariana Trench include:

Dumbo Octopus

The dumbo octopus, a unique resident of the Mariana Trench
The dumbo octopus, a unique resident of the Mariana Trench

The dumbo octopus is a small, pelagic umbrella octopus that resembles Dumbo from the 1941 Disney film. It was first discovered around 1883. The octopus’ gelatinous body allows it to live at extreme, high-pressure depths.

Angler Fish

The striped angler fish, a creature found very deep in the Mariana Trench
The striped angler fish, a creature found very deep in the Mariana Trench

The angler fish is one of the most famous animals living in the Mariana Trench, mostly due to the success of the Disney film Finding Nemo. It’s known for its distinctive protruding light that’s used to attract prey and mates.

Frilled Shark

The Frilled Shark is an eery-looking deep sea predator

Credit: Citron

This incredible shark species has an eel-like body and is dark brown to grey in color. The sharks live near the ocean floor, such as in and around the Mariana Trench. They’re sometimes described as “living fossil” due to their eery appearance.

Goblin Shark

The Goblin Shark has weird extruding nose
The Goblin Shark and its unusual protruding nose

The Goblin shark is a rare species of shark that’s pink-toned and between 10-13 feet in length. They are rarely seen by humans because they live at incredible depths, around 100 meters or 330 feet. What their protruding nose is for is a subject of debate in the scientific community.

Some of the other species living in the Mariana Trench include:

  • Telescope Octopus
  • Zombie Worms
  • Barreleye Fish
  • Deep-sea Dragonfish
  • Sea Cucumber
  • Mariana Snailfish
  • Benthocodon Jellyfish
  • Deep-sea Hatchetfish
  • Vampire Squid
  • Bacteria
  • Small Crustaceans
  • Shrimp-like amphipods
  • Microbes and microorganisms
  • Plankton

New species are always being discovered by scientists in the Trench, including a recently-discovered unknown fish species.

Mariana Trench Facts

  • The Trench is deeper than Mount Everest is tall.
  • The Mariana Trench is 180 million years old.
  • It is home to a strange plethora of creatures.
  • It was discovered in 1875.
  • The deepest part of the trench is known as the Challenger Deep.
  • Parts of the Trench are hot, and parts are cold.
  • It is a U.S. National Monument.
  • The United States has jurisdiction over the Trench. 
  • It is nearly 30,000 feet deeper than the Grand Canyon in the United States. 

Mariana Trench and Waste Disposal 

In the 1970s, the Mariana Trench was proposed as a site for nuclear waste disposal (as have other deep, oceanic trenches). In 1972, some posed the possibility that subduction (or the process in which one tectonic plate moves beneath another) could push the waste down into the Earth’s mantle. But, this kind of dumping is prohibited by international law, and the Mariana Trench is protected in U.S. territory as a National Monument. 

FAQs 

Has anyone been down the Mariana Trench?

Yes, in the history of exploration, twenty-seven people have been down into the Challenger Deep, the deepest point in the Mariana Trench. The first expedition to its depths was in 1960 by Jacques Piccard and Don Walsh. 

What lives at the bottom of the Mariana Trench? 

Amazingly, there are organisms capable of living 36,000 feet below sea level. These include shrimp, sea cucumbers, and crustaceans, like the giant amphipod, and large foraminifera, single-celled organisms. The deepest-living fish in the trench, snailfish, was discovered at around 26,000 feet. 

Can a human survive in the Mariana Trench?

No, a human could not survive in the Mariana Trench. Besides requiring 36,000 feet of diving to reach the bottom, the incredible water pressure in the trench makes any human free-diving an impossibility. It is more than 1,000x the pressure at sea level. 

How cold is the Mariana Trench?

You might be surprised to learn that the water temperature is usually between 34 and 39 degrees F (or 1-4 degrees C). 

Why can’t you swim up from the bottom of the ocean?

You can’t swim up from the bottom of the ocean because of the pressure. If you swam straight up from the bottom of the Mariana Trench, you’d die due to the pressure change, an injury known as a barotrauma or decompression illness. 

How was the Mariana Trench formed? 

The Mariana Trench was formed through subduction. Specifically when the Pacific plate sunk under the Philippine plate.