Mariana Trench

The Mariana Trench is a deep oceanic trench located on the ocean floor in the western Pacific Ocean, near the Mariana Islands. It is the deepest known location in the world's oceans, with a depth of approximately 11 kilometres.

A trench is a long, narrow depression on the ocean floor formed where one tectonic plate sinks beneath another. The Mariana Trench has a V-shaped profile and extends for roughly one thousand kilometres in length, with a width of several kilometres.

Geological Formation

The trench was created by subduction: the heavy Pacific Plate sinks beneath the Mariana/Philippine Plate. As the plate descends, the oceanic crust beneath it melts, creating the trench. The same process produces earthquakes and volcanoes along the arc of the Mariana Islands.

Challenger Deep

The deepest part of the trench is called Challenger Deep, located in the southern section near Guam. The name comes from the British research vessel HMS Challenger, which surveyed the depth around the 1870s. Modern sonar measurements indicate a depth of approximately 10,900–11,000 metres.

Human Visits

In 1960, Jacques Piccard and Don Walsh reached Challenger Deep using the bathyscaphe Trieste. In 2012, filmmaker James Cameron descended alone in a specialized submersible. Since 2019, repeat expeditions have visited the bottom, taking measurements and collecting samples.

Ecosystem and Life

At the bottom of the trench, water pressure exceeds 1,000 times that of sea level, and no sunlight penetrates. Bacteria, amphipods (small armoured crustaceans), and several fish species adapted to extreme pressure inhabit the area. Scientists have also found plastic waste on the floor, indicating that human pollution has reached the most remote locations.

Legal Status

A large portion of the trench lies within the territorial waters of the Mariana Islands, a United States territory. In 2009, the United States designated part of the area as a protected natural monument (Marianas Trench Marine National Monument).