Where is the Mariana Trench located?

The Mariana Trench is a deep-sea trench in the floor of the western North Pacific Ocean , and is the deepest trench on Earth. It extends from southeast of Guam to the northwest of the Mariana Islands. The trench is part of the western Pacific system of oceanic trenches, found in subduction zones where two adjacent tectonic plates collide. The Pacific Plate is being forced under the smaller Mariana Plate, creating this deep-sea trench . The Mariana Trench is part of the Ring of Fire , a seismically active belt of earthquake epicenters, volcanoes, and tectonic plate boundaries that fringes the Pacific basin.

How deep is the Mariana Trench?

The Mariana Trench, in the western North Pacific Ocean, is the deepest known trench on Earth. It stretches for over 1,580 miles, with a mean width of 43 miles. The greatest depths are in Challenger Deep, a steep-walled valley southwest of Guam. While various measurements have been taken, the Challenger Deep reaches an estimated depth of 35,876 feet (10,935 meters), which is roughly 6.8 miles below sea level, making it the lowest point on Earth. The Mariana Trench was formed by the process of subduction, where the Pacific Plate is forced under the Mariana Plate.

What causes ocean trenches like the Mariana Trench to form?

The Mariana Trench, the deepest part of the world's oceans, formed through subduction , a process where one tectonic plate is forced beneath another. In this case, the older, denser Pacific Plate is subducting beneath the smaller Mariana Plate, creating a deep-sea trench . As the Pacific Plate descends into the Earth's mantle, it bends and forms a V-shaped trench. The shape and depth of the trench are influenced by factors such as pressure, age, density, and the speed of the colliding plates. The Mariana Trench is part of a larger system of oceanic trenches associated with volcanic island arcs. As the Pacific Plate subducts, it melts and forms magma, which rises to the surface, creating volcanic islands like the nearby Mariana Islands.

What kind of animals live in the Mariana Trench?

The Mariana Trench is a deep-sea trench in the western North Pacific Ocean, east of the Mariana Islands, and is the deepest known depression of its kind. Deep-sea organisms, such as mussels, large bivalve clams, and vestimentiferan worms, thrive in the Mariana Trench. These organisms are supported by bacteria that oxidize sulfur and derive chemical energy from the reaction. They are referred to as chemoautotrophic, or chemosynthetic, as opposed to photosynthetic, organisms. The extreme hydrostatic pressure in the Mariana Trench presents a significant environmental challenge to its inhabitants. With each 10-meter increase in depth, hydrostatic pressure increases by approximately one atmosphere. Animals at these depths lack air compartments, such as lungs or swim bladders, to overcome this challenge.

Why is studying the Mariana Trench important for scientists?

The Mariana Trench is a deep-sea trench in the floor of the western North Pacific Ocean and the deepest such trench known on Earth. It is a prime example of a subduction zone , where the Pacific Plate is forced below the Mariana Plate. Studying the Mariana Trench is important because it helps scientists understand the physicochemical parameters defining life on Earth and may provide insight into how life on Earth originated. The study of the trench has yielded the discovery of potentially valuable bottom resources, and knowledge of undersea volcanism, as well as of marine life near active vents associated with centers of tectonic activity, has been greatly expanded.

Mariana Trench

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Images

Labeled geological cross-section diagram of the Mariana Arc, showing island arc, Mariana Trench, Pacific Plate, old ocean crust, and crustal spreading zones.

Colorful soft corals and sponges cover the summit of the East Diamante submarine volcano in the Mariana Trench, with several orange and yellow fish swimming among the reef.

Map of the western Pacific Ocean highlighting the location of the Mariana Trench, shown as an orange curved line east of the Mariana Islands and Guam. The map includes surrounding countries such as Japan, the United States, Australia, New Zealand, and the Federated States of Micronesia, with major oceanic and sea regions labeled.

Mariana forearc: Northwest Eifuku volcano

Quick Facts

Also called:: Marianas Trench

On the Web:: National Center for Biotechnology Information - PubMed Central - Fungal Abundance and Diversity in the Mariana Trench, the Deepest Ecosystem on Earth (Oct. 20, 2026)

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Mariana Trench

trench, Pacific Ocean

Also known as: Marianas Trench

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Nov. 3, 2026 •History

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Top Questions

What is the Mariana Trench?
The Mariana Trench is a deep-sea trench in the floor of the western North Pacific Ocean, located mostly east and south of the Mariana Islands. It is the deepest such trench known on Earth.

The Mariana Trench is an arcing depression that stretches for more than 1,580 miles (2,540 km), with a mean width of 43 miles (69 km). The greatest depths are reached in Challenger Deep, a smaller steep-walled valley on the floor of the main trench southwest of Guam. The trench was formed through subduction, a process in which the Pacific Plate is forced below the Mariana Plate.
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Where is the Mariana Trench located?
The Mariana Trench is a deep-sea trench in the floor of the western North Pacific Ocean, and is the deepest trench on Earth. It extends from southeast of Guam to the northwest of the Mariana Islands. The trench is part of the western Pacific system of oceanic trenches, found in subduction zones where two adjacent tectonic plates collide. The Pacific Plate is being forced under the smaller Mariana Plate, creating this deep-sea trench. The Mariana Trench is part of the Ring of Fire, a seismically active belt of earthquake epicenters, volcanoes, and tectonic plate boundaries that fringes the Pacific basin.
7 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How deep is the Mariana Trench?
The Mariana Trench, in the western North Pacific Ocean, is the deepest known trench on Earth. It stretches for over 1,580 miles, with a mean width of 43 miles. The greatest depths are in Challenger Deep, a steep-walled valley southwest of Guam.

While various measurements have been taken, the Challenger Deep reaches an estimated depth of 35,876 feet (10,935 meters), which is roughly 6.8 miles below sea level, making it the lowest point on Earth. The Mariana Trench was formed by the process of subduction, where the Pacific Plate is forced under the Mariana Plate.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What causes ocean trenches like the Mariana Trench to form?
The Mariana Trench, the deepest part of the world's oceans, formed through subduction, a process where one tectonic plate is forced beneath another. In this case, the older, denser Pacific Plate is subducting beneath the smaller Mariana Plate, creating a deep-sea trench. As the Pacific Plate descends into the Earth's mantle, it bends and forms a V-shaped trench. The shape and depth of the trench are influenced by factors such as pressure, age, density, and the speed of the colliding plates.

The Mariana Trench is part of a larger system of oceanic trenches associated with volcanic island arcs. As the Pacific Plate subducts, it melts and forms magma, which rises to the surface, creating volcanic islands like the nearby Mariana Islands.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What kind of animals live in the Mariana Trench?
The Mariana Trench is a deep-sea trench in the western North Pacific Ocean, east of the Mariana Islands, and is the deepest known depression of its kind.

Deep-sea organisms, such as mussels, large bivalve clams, and vestimentiferan worms, thrive in the Mariana Trench. These organisms are supported by bacteria that oxidize sulfur and derive chemical energy from the reaction. They are referred to as chemoautotrophic, or chemosynthetic, as opposed to photosynthetic, organisms.

The extreme hydrostatic pressure in the Mariana Trench presents a significant environmental challenge to its inhabitants. With each 10-meter increase in depth, hydrostatic pressure increases by approximately one atmosphere. Animals at these depths lack air compartments, such as lungs or swim bladders, to overcome this challenge.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why is studying the Mariana Trench important for scientists?
The Mariana Trench is a deep-sea trench in the floor of the western North Pacific Ocean and the deepest such trench known on Earth. It is a prime example of a subduction zone, where the Pacific Plate is forced below the Mariana Plate.

Studying the Mariana Trench is important because it helps scientists understand the physicochemical parameters defining life on Earth and may provide insight into how life on Earth originated. The study of the trench has yielded the discovery of potentially valuable bottom resources, and knowledge of undersea volcanism, as well as of marine life near active vents associated with centers of tectonic activity, has been greatly expanded.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Mariana Trench, deep-sea trench in the floor of the western North Pacific Ocean, the deepest such trench known on Earth, located mostly east as well as south of the Mariana Islands. It is part of the western Pacific system of oceanic trenches coinciding with subduction zones—points where two adjacent tectonic plates collide, one being forced below the other. An arcing depression, the Mariana Trench stretches for more than 1,580 miles (2,540 km) with a mean width of 43 miles (69 km). The greatest depths are reached in Challenger Deep, 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. national monument in 2009.

Measuring the greatest depths in the Mariana Trench is an exceedingly difficult task, given the technical challenges of delivering instrumentation to such a remote location and then obtaining accurate readings. The first attempt was made in 1875 during the Challenger Expedition (1872–76), when a sounding of 26,850 feet (8,184 metres) was obtained near the southern end of the trench. In 1899 Nero Deep (31,693 feet [9,660 metres]) was discovered southeast of Guam. That sounding was not exceeded until a 32,197-foot (9,813-metre) hole was found in the vicinity 30 years later. In 1957, during the International Geophysical Year, the Soviet research ship Vityaz sounded a new world record depth of 36,056 feet (10,990 metres) in Challenger Deep. That value was later increased to 36,201 feet (11,034 metres). Since then several measurements of the Challenger Deep have been made, using increasingly sophisticated electronic equipment. Notable among these is the depth of 35,840 feet (10,924 metres) reported by a Japanese expedition in 1984 and one of 36,070 feet (10,994 metres) obtained by a U.S. research team in 2011. In addition, another deep hole—originally called HMRG Deep (for Hawaii Mapping Research Group, the discoverers of the location) and later renamed Sirena Deep—is situated south of Guam and east of Challenger Deep. First encountered in 1997, its depth has been reported variously as 34,911 and 35,463 feet (10,641 and 10,809 metres).

The first descent to the bottom of the Mariana Trench took place on January 23, 1960. The French-built U.S. Navy-operated bathyscaphe Trieste—with Swiss ocean engineer Jacques Piccard (who helped his father, Auguste Piccard, design the bathyscaphe) and U.S. naval officer Don Walsh aboard—made a record dive to 35,814 feet (10,916 metres) in Challenger Deep. The next person to descend into that location did so more than 50 years after Piccard and Walsh. On March 26, 2012, Canadian filmmaker James Cameron piloted the submersible Deepsea Challenger (which he had helped design) to 35,756 feet (10,898 metres), in the process establishing a new world record depth for a solo descent.

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The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by John P. Rafferty.