Earth is a cornucopia of extremes—extreme temperatures, extreme habitats, and extreme beauty and wonder. One of the most intriguing extremes on Earth is the Mariana Trench, the deepest known point on the planet.

The Mariana Trench is full of secrets. What humans do know about its depths continues to puzzle and amaze, from the creatures that live there to the natural phenomena that occur on the sea floor.

Travel to the deepest point on Earth, and do it from the comfort of your home. Here’s a quick dive into the Mariana Trench.

What is the Mariana Trench?

Credit: NASA

The Mariana Trench (also called the Marianas Trench) is a deep, crescent-shaped cleft in the floor of the western Pacific Ocean. The trench is located approximately 124 miles east of the Mariana Islands, a string of islands south of Japan and east of the Philippines.  

The Mariana Trench is one of many subduction zones—areas where two tectonic plates collide and one sinks below the other—on the ocean floor. It is wider than 50 kilometers (31 miles) at its widest point, stretches nearly 1,585 miles from end to end, and the deepest point in the trench (the Challenger Deep) is estimated to be almost seven miles. To put that in perspective, if Mount Everest were dropped into the ocean at the deepest point of the Mariana Trench, it would still sit under more than a mile of water. Water above the Mariana Trench exerts a pressure of 15,750 psi, more than 1,000 times the standard atmospheric pressure at sea level.

We still know very little about the Mariana Trench. That’s most likely due to the trench only being accurately measured in 1951 and the inhospitable nature of the ocean at that depth.

Discovering and exploring the Mariana Trench

Credit: Philippe Kurlapski / Wikimedia

The Mariana Trench was first discovered by the British Survey ship HMS Challenger in 1875. The greatest depth recorded at the time was only 8,184 meters (5 miles or 26,850 feet). It wouldn’t be properly measured for another 100 years.

In 1951, the HMS Challenger II used echo sounding to find an even deeper point in the Mariana Trench, and the Challenger Deep was named after the ship that discovered it.

Man’s curiosity tends to lead him to strange places, and it was this curiosity that led Jacques Piccard and Don Walsh to the ocean floor (10,916 meters) of the Challenger Deep in their submersible the Trieste in 1960.

There have been only three other missions to the depths of the Challenger Deep since the initial trip taken by the Trieste. The next two were unmanned (in 1996 and 2009), and the last was taken by film director James Cameron in 2012 aboard the Deepsea Challenger.

While humans may not travel to the Mariana Trench and the Challenger Deep often, scientists are using advanced technology to help us understand the mysteries hidden in its depths.

Surprises found in the Mariana Trench

Credit: 3dmentat / depositphotos

It’s no wonder that man hasn’t ventured to the sea floor of the Mariana Trench. Immense pressures and cold temperatures make it an inhospitable place for creatures as soft and warm as humans. That said, those who have been to the bottom of the trench were surprised to find some forms of life living at such depths.

Piccard and Walsh reported seeing large creatures—flatfish and shrimp—living at the bottom of the Mariana Trench, but those reports were never confirmed and were later questioned.

Cameron’s solo trip to the Challenger Deep was more revealing, and video evidence confirmed that there were a few strange-but-recognizable creatures living in the high-pressure environment. No sea monsters or giant squid were spotted, but the following creatures were confirmed:

  • Amphipods – Shrimp-like crustaceans were found in abundance swimming around the waters of the Challenger Deep, some more than a foot long.
  • Echinoderms – Small, stick-like sea cucumbers were spotted on the sea floor.
  • Foraminifera – Amoeboid protists that live under calcium carbonate shell layers on the ocean floor.
  • Xenophyophores – Massive single-celled organisms living on the floor of the Mariana Trench.
  • Jellyfish – Surprisingly, a jellyfish was spotted floating by in the captured footage.

Continued exploration of the Mariana Trench

Credit: YukoF / shutterstock

Again, it’s not easy to rove and explore the sea floor of the trench or the Challenger Deep. But scientists are certain there are still a number of undiscovered creatures waiting to be found.

New species and surprising findings are being discovered all along the Mariana Trench expanse. Humans are bound to continue exploring the depths as technology evolves and mankind’s drive to explore the unknown keeps us searching for new discoveries. Only time will tell what wonders we’ll uncover as we map, measure, and document the Mariana Trench in the future.