The Mariana Trench: All You Need to Know

Ocean trenches are steep depressions in the deepest parts of the ocean where old ocean crust from one tectonic plate is pushed beneath another plate, raising mountains, causing earthquakes, and forming volcanoes on the seafloor and on land.

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 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)

The deepest spot 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.

Formation

Located between Hawaii and the Philippines, the Mariana Trench is shaped like a crescent in the western Pacific Ocean. It is but one part of a global network of deep scars that cut across the ocean floor and formed from a process called subduction. In the case of the Mariana Trench, the western edge of the Pacific Plate was thrust beneath the smaller Mariana Plate to the west, creating a deep fracture. Molten material then rose through volcanoes near the trench, building the nearby Mariana Islands.

The Mariana Trench is one of about 30 subduction zones that make up the hadal zone, which consists of depths 6,000 – 11,000 meters.

After it, 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 which lies 124 miles to the east of Challenger Deep. It, too, is located in the Mariana Trench and is 35,151 ft or 10,714 meters. 

Discovery and Exploration

The Mariana Trench Marine National Monument was first sounded and acknowledged as the deepest point on Earth in 1875 during the Challenger Expedition. At the time, it was believed to be 26,850 feet or 8,184 meters deep. More than 20 years later, another expedition on the USS Nero re-recorded the depth closer to 31,614 feet of 9.636 meters. Today, the depth has been confirmed at closer to 36,200 feet.

Located east of the Mariana Islands, it was aptly named after the nearby Mariana Islands (which in turn are named after Queen Mariana of Austria).

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

Nuclear Waste Disposal 

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

“We still think of the deep ocean as being this remote and pristine realm, safe from human impact, but our research shows that, sadly, this could not be further from the truth.”

Alan Jamieson

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.

It is a smaller steep-walled valley on the floor of the main trench southwest of Guam. The Mariana Trench, which is situated within the territories of the U.S. dependencies of the Northern Mariana Islands and Guam, was designated a U.S. 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 U.S naval officer Don Walsh, made the first dive into the trench and were the first people to reach the bottom. The first solo manned dives to the deepest part of planet was completed in 2012 by filmmaker James Cameron onboard the Deepsea Challenger during the Deepsea Challenge expedition. The filmmaker solo-piloted the submersible the Deepsea Challenger, filming footage for National Geographic. He dove just shy of the original record, reaching a depth of 35,787 feet (10,908 m). In 2019, explorer and businessman Victor Vescovo piloted the DSV Limiting Factor, breaking the record for deepest dive into Challenger Deep. He descended 35,853 feet (10,927 m). Since mid-2022, twenty-seven people have traveled to the bottom of the trench. 

Challenger Deep had been a significant monumental landmark in the field of oceanography and marine biology.

Mariana Trench Animals

As mentioned, the deepest parts of the ocean are named ‘the hadal zone’ after the Greek underworld Hades. Scientists decided to name this zone after Hades because it’s the underworld of the ocean – with harsh conditions.

But these conditions are what is normal for the animals down there. They like the cold, the dark, and the high pressure and are quite happy to live their lives way down deep. And they’re not monsters of the underworld at all – many can be quite beautiful and certainly interesting.

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 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 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

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 fossils” due to their eel-like appearance.

Goblin Shark

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.

4 Mind-Boggling Mariana Trench Facts

1. The Trench is deeper than Mount Everest is tall.
2. The Mariana Trench is 180 million years old.
3. Despite its depth, parts of the trench are hot, and parts are cold.
4. It is nearly 30,000 feet deeper than the Grand Canyon in the United States. 

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