The Mariana Trench
The deepest place on Earth: a subduction trench reaching 10,935 meters at Challenger Deep, with its own fauna, chemistry, and a handful of human visitors.
_over_the_Marianas_Trench,_23_January_1960_(NH_96797).jpg)
The Mariana Trench, in the western Pacific near Guam, contains the deepest known point of the world ocean: the Challenger Deep, sounding about 10,935 meters — roughly 2,000 meters deeper than Everest is tall. It is the surface expression of a subduction zone, where the Pacific Plate dives beneath the Mariana Plate; plate tectonics explains the trench as the surface trace of that dive.
Pressure, cold, and dark
At the bottom, pressure exceeds 1,000 atmospheres — about 1.1 metric tons on every square centimeter — and the temperature hovers just above freezing. Every 10 meters of depth adds roughly one atmosphere of pressure, so a body at the bottom bears about 1,100 times the surface load. The water column is functionally lightless below 1,000 meters; the only energy inputs are organic debris sinking from above and chemosynthesis at hydrothermal and cold-seep sites.
Who has been down
Jacques Piccard and Don Walsh reached the bottom in the bathyscaphe Trieste in 1960; James Cameron soloed there in 2012 in the Deepsea Challenger; Victor Vescovo has made repeated dives since 2019 in the two-person-limiting submersible Limiting Factor. More people have walked on the Moon (12) than have stood on the Challenger Deep floor (a few dozen).
Life under pressure
Trenches host amphipods, holothurians (sea cucumbers), xenophyophores — giant single-celled organisms — and snailfish, the deepest-living fish recorded near 8,300 m, below which physiological limits of cellular respiration under pressure appear to exclude vertebrates. Microbes dominate the biomass, metabolizing organic matter that sinks from the surface — food webs and trophic levels with the engine one kilometer overhead. Related reading: ocean currents, tidal locking.
Tags
deep sea geology ocean subduction