Facts about the deepest place on Earth

The Mariana Trench, an ocean trench that reaches depths of up to about 11,000 meters, has living creatures and even plastic bags.

Director James Cameron sits in a miniature model of the capsule at an exhibition in Sydney in 2018. Photo: Saeed Khan/AFP/Getty

While the land is home to huge mountains and valleys, similar structures exist underwater. One of the most remarkable structures is the Mariana Trench, a fissure in the western Pacific Ocean that is more than 2,540 km long. It is home to the Challenger Deep, the deepest point ever recorded on Earth, at a depth of about 11,000 m. That is nearly three times the depth of the Titanic and greater than the height of Mount Everest, the world's tallest mountain.

James Cameron is one of the few people to descend the Challenger Deep.

The first dive to the Challenger Deep took place in 1960 with the submersible Trieste. During the dive, passengers Jacques Piccard and Don Walsh were amazed to see living creatures. James Cameron, director of the 1997 film "Titanic", was the next deep-sea explorer. He piloted a submersible to a depth of about 10,908 m, setting a world record in 2012.

According to the National Oceanic and Atmospheric Administration (NOAA), for every 10 meters below the ocean's surface, the pressure increases by 1 atmosphere. An atmosphere is a unit of pressure, equivalent to 14.7 pounds (6.4 kg) per square inch (6.5 cm2). This means that the Challenger can withstand the pressure equivalent to 50 massive Boeing 747 aircraft.

Detect plastic bags

Another explorer who has descended to the Challenger Deep is Victor Vescovo, a Texas investor who descended 10,927 meters and set a new world record in 2019. Vescovo has provided a sobering account of the human impact on seemingly inaccessible places: He said he saw plastic bags and candy wrappers in the Mariana Trench.

Jellyfish observed during the Enigma expedition at a depth of 3,700 m in the Mariana Trench. Photo: NOAA Office of OER

The Challenger Deep is in the "hadalpelagic zone"

Like Earth's atmosphere, the ocean can be divided into several layers. According to NOAA, the uppermost part is called the epipelagic zone, or sunlit zone, which extends down to about 650 feet (200 m) below the surface. The mesopelagic zone, also known as the twilight zone, extends from the end of the sunlit zone down to about 3,000 feet (1,000 m). Next is the bathypelagic zone, or midnight zone, and the abyssopelagic zone, or abyssal zone, which ranges from 13,000 to 20,000 feet (4,000 to 6,000 m). In the abyssal zone, very little life can exist, the water is completely dark, and it is extremely cold.

But at around 11,000 metres deep, the Challenger Deep lies even deeper, in the hadalpelagic zone. This area is named after Hades, the Greek god of the underworld.

The existence of unique aquatic species and mud volcanoes

The hadalpelagic zone is one of the least explored habitats on Earth. At record depths and without sunlight, scientists once thought nothing could survive there. But that wasn’t true.

"Even at the bottom, life exists. In 2005, tiny single-celled organisms called foraminifera, a type of plankton, were discovered in the Challenger Deep," according to NOAA. Experts have also discovered colorful rock formations and sea cucumbers.

According to NOAA, the Mariana Trench’s series of underwater mud volcanoes and hydrothermal vents also contribute to unusual life forms. Despite the highly acidic hot water from the hydrothermal vents in the mud volcanoes, many strange animals and microscopic organisms survive. In fact, they benefit from the nutrient-rich water from the vents in the absence of sunlight.

Hydrothermal vents under the Mariana Trench in the Pacific Ocean during a 2016 expedition. Photo: NOAA Office of Ocean Exploration and Research

Exact depth unknown

Humans have been exploring the ocean surface for tens of thousands of years, but only about 20% of the seafloor has been mapped, according to 2022 data from NOAA. Researchers have made great efforts to study the Mariana Trench in detail, but it's not easy. Because of the vastness and record-breaking depth of the ocean floor, they have to rely on sonar technology to try to get a full picture of what's underneath.

The first manned dive in 1960 estimated the Challenger Deep to be 10,911 m deep, according to the Guinness Book of World Records. With ever-improving equipment and technology, the most recent update in 2021 estimated the Challenger Deep's depth to be approximately 10,935 m.

Thu Thao (According to CNN )

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