While thousands of climbers have successfully scaled Mount Everest, the highest point on Earth, only two people have descended to the planet’s deepest point, the Challenger Deep in the Pacific Ocean’s Mariana Trench.

Located in the western Pacific east of the Philippines and an average of approximately 124 miles (200 kilometers) east of the Mariana Islands, the Mariana Trench is a crescent-shaped scar in the Earth’s crust that measures more than 1,500 miles (2,550 kilometers) long and 43 miles (69 kilometers) wide on average. The distance between the surface of the ocean and the trench’s deepest point—the Challenger Deep, which lies about 200 miles (322 kilometers) southwest of the U.S. territory of Guam—is nearly 7 miles (11 kilometers). If Mount Everest were dropped into the Mariana Trench, its peak would still be more than a mile (1.6 kilometers) underwater.

The Mariana Trench is part of a global network of deep troughs that cut across the ocean floor. They form when two tectonic plates collide. At the collision point, one of the plates dives beneath the other into the Earth’s mantle, creating an ocean trench.

The depths of the Mariana Trench were first plumbed in 1875 by the British ship H.M.S. Challenger as part of the first global oceanographic cruise. The Challenger scientists recorded a depth of 4,475 fathoms (about five miles, or eight kilometers) using a weighted sounding rope. In 1951, the British vessel H.M.S. Challenger II returned to the spot with an echo-sounder and measured a depth of nearly 7 miles (11 kilometers).

The majority of the Mariana Trench is now a U.S. protected zone as part of the Marianas Trench Marine National Monument, established by President George W. Bush in 2009. Permits for research in the monument, including in the Sirena Deep, have been secured from the U.S. Fish and Wildlife Service. Permits for research in the Challenger Deep have been secured from the Federated States of Micronesia.



Because of its extreme depth, the Mariana Trench is cloaked in perpetual darkness and the temperature is just a few degrees above freezing. The water pressure at the bottom of the trench is a crushing eight tons per square inch—or about a thousand times the standard atmospheric pressure at sea level. Pressure increases with depth.

The first and only time humans descended into the Challenger Deep was more than 50 years ago. In 1960, Jacques Piccard and Navy Lt. Don Walsh reached this goal in a U.S. Navy submersible, a bathyscaphe called the Trieste. After a five-hour descent, the pair spent only a scant 20 minutes at the bottom and were unable to take any photographs due to clouds of silt stirred up by their passage.

Until Piccard and Walsh’s historic dive, scientists had debated whether life could exist under such extreme pressure. But at the bottom, the Trieste‘s floodlight illuminated a creature that Piccard thought was a flatfish, a moment that Piccard would later describe with excitement in a book about his journey.

“Here, in an instant, was the answer that biologists had asked for the decades,” Piccard wrote. “Could life exist in the greatest depths of the ocean? It could!”


While the Trieste expedition laid to rest any doubts that life could exist in the Mariana Trench, scientists still know very little about the types of organisms that reside there. In fact, some question whether Piccard’s fish was actually a form of sea cucumber. It is thought that the pressure is so great that calcium can’t exist except in solution, so the bones of vertebrates would literally dissolve. No bones, no fish. But nature has also proven scientists wrong many times in the past with its remarkable capacity for adaptation. So are there fish that deep? Nobody knows, and this is the whole point of the DEEPSEA CHALLENGE project, to find answers to such fundamental questions in this website

In recent years, deep-ocean dredges and unmanned subs have glimpsed exotic organisms such as shrimp-like amphipods, and strange, translucent animals called holothurians. But scientists say there are many new species awaiting discovery and many unanswered questions about how animals can survive in these extreme conditions. Scientists are particularly interested in microorganisms living in the trenches, which they say could lead to breakthroughs in biomedicine and biotechnology.

The Mariana Trench’s microscopic inhabitants might even shed light on the emergence of life on Earth. Some researchers, such as Patricia Fryer et alat University of Hawaii, have speculated that serpentine mud volcanoes located near ocean trenches might have provided the right conditions for our planet’s first life-forms. Additionally, studying rocks from ocean trenches could lead to a better understanding of the earthquakes that create the powerful and devastating tsunamis seen around the Pacific Rim, geologists say.

6 incredible facts about the Challenger Deep, the deepest point on Earth

6 incredible facts about the Challenger Deep, the deepest point on Earth

Just as Earth’s land surface has enormous peaks and valleys, the oceanic world has similarly varied topography.

Perhaps the most intriguing of these features is the Mariana Trench — a chasm in the western Pacific Ocean that spans more than 1,580 miles (2,540 kilometers) and is home to the Challenger Deep, the deepest known point on Earth’s surface that plunges more than 36,000 feet (about 11,000 meters) underwater.

That’s nearly three times deeper than the site where the wreckage of the RMS Titanic lies in the Atlantic Ocean, and it’s deeper than Mount Everest is tall.

6 incredible facts about the Challenger Deep, the deepest point on Earth

Here are some fascinating facts about this deep-sea phenomenon.

1. ‘Titanic’ director James Cameron is one of the few people who have visited

Few human expeditions have ventured to the Challenger Deep.

The first came in 1960 with the historic dive of the Trieste bathyscaphe, a type of free-diving submersible. During the dive, passengers Jacques Piccard and Don Walsh said they were stunned to see living creatures where scientists once imagined it was impossible for anything to survive.

“Right away, all of our preconceptions about the ocean were blown out the window,” Dr. Gene Feldman, an oceanographer emeritus at NASA, previously told CNN. He spent more than 30 years at the space agency.

James Cameron, director of the 1997 film “Titanic,” was the next deep-sea explorer to follow. He piloted a submersible — one that he personally had helped design — to about 35,787 feet (10,908 meters), setting a world record in 2012.

2. A plastic bag was found in the trench

Another explorer who returned to the site was Victor Vescovo, a Texas investor who journeyed 35,853 feet (10,927 meters) down and claimed a world record in 2019.

Vescovo gave depressing insight into humankind’s impact on these seemingly untouchable remote locations when he observed a plastic bag and candy wrappers at the bottom of the Mariana Trench.

A handful of explorers have trekked to the Challenger Deep since then, but the expeditions are not common — and the journey is extremely dangerous.

For every 33 feet (10 meters) traveled beneath the ocean’s surface, the pressure on an object increases by one atmosphere, according to National Oceanic and Atmospheric Administration. An atmosphere is a unit of measure that’s 14.7 pounds per square inch. A trip to the Challenger Deep can put a vessel under pressure that is “equivalent to 50 jumbo jets,” Feldman noted.

3. It lies in the hadal zone, named for the god of the underworld

Much like the Earth’s atmosphere, the ocean can be described in terms of layers.

The uppermost portion is called the epipelagic zone, or the sunlight zone, and extends just 660 feet (200 meters) below the water’s surface, according to NOAA.

The mesopelagic zone, or the so-called twilight zone, stretches from the end of the sunlight zone to about 3,300 feet (1,000 meters).

Then there’s the bathypelagic zone, also called the midnight zone, and, beneath that, the abyssopelagic zone — as in, the abyssal zone — that extends from 13,100 feet (4,000 meters) to 19,700 feet (6,000 meters). That’s nearly 4 miles underwater. Within the abyssal zone, few life-forms can survive, the water is completely devoid of light, and temperatures are near freezing.

But the Challenger Deep lies even further — in the hadalpelagic zone, or the hadal zone. It’s named for Hades, the Greek god of the underworld thought to rule over the dead.

4. It’s home to unique aquatic life and mud volcanoes

The hadal zone is one of the least explored habitats on Earth. At bone-crushing depths with no sunlight, it was long thought that nothing could survive there.

But that belief has been dispelled.

“Even at the very bottom, life exists. In 2005, tiny single-celled organisms called foraminifera, a type of plankton, were discovered in the Challenger Deep,” according to NOAA.

Discoveries at the Challenger Deep have included colorful rocky outcrops and bottom-dwelling sea cucumbers.

A series of undersea mud volcanoes and hydrothermal vents in the Mariana Trench also support unusual life-forms, according to NOAA. Despite the highly acidic and infernally hot water produced by hydrothermal vents in mud volcanoes, exotic species and microscopic organisms there are able to survive.

In the absence of sunlight, the creatures instead benefit from the nutrient-rich waters belched out from hydrothermal vents. The life-supporting medium results from chemical reactions between the seawater and magma rising from beneath the ocean floor.

5. The Mariana Trench was designated as a US national monument in 2009

The Marianas Trench Marine National Monument was established in 2009, in part to protect the rare organisms that thrive within its depths.

Objects of interest include the submerged ecosystem and its life-forms, such as deep-sea shrimp and crabs, and — higher up in the water column — stony coral reefs.

“A great diversity of seamount and hydrothermal vent life (is) worth preservation,” according to NOAA.

The entire national monument protects about 95,000 square miles (246,049 square kilometers).

6. It’s difficult to know just how deep the trench goes

The ocean floor remains one of the most mysterious places in the universe.

In fact, “we have better maps of the moon and Mars than we do of our own planet,” Feldman previously told CNN.

Though people have been exploring the ocean’s surface for tens of thousands of years, only about 20% of the seafloor has been mapped, according to 2022 figures from NOAA.

Given high interest in the Mariana Trench, however, researchers have made several efforts to give increasingly detailed pictures of its features. But that’s not easy: Due to the vastness and deepness of the bottommost ocean zone, scientists must rely on sonar, or acoustic, technology to attempt to give a full picture of what’s below.

Because instrumentation and technology are constantly improving, the estimated depth of the Challenger Deep has been updated as recently as 2021 to about 35,876 feet (10,935 meters).