How Deep Is the Mariana Trench? (The Ocean's Lowest Point, in Numbers)

Challenger Deep, the lowest point in the Mariana Trench, sits 10,935 meters (35,876 feet) below sea level. That's deeper than Mount Everest is tall — by 2,087 meters. Pressure at the bottom reaches 1,086 bars, or 1,086 times the pressure at sea level. Only four crewed descents have reached it. More people have walked on the Moon.

Here's what that depth actually means.

The trench, mapped

The Mariana Trench is a 2,550 km crescent-shaped scar in the Pacific Ocean floor, east of the Mariana Islands. It formed where the Pacific Plate subducts under the Philippine Plate — the Pacific Plate pushes down at about 4 cm per year.

Challenger Deep is the trench's southernmost and deepest pocket. 11 km wide, 2 km long, 10,935 m deep.

The pressure problem

At 10,935m, pressure is ~1,086 bars — over 8 tons per square inch. That's:

• Equivalent to the weight of 50 jumbo jets stacked on every square meter of your body
• ~1,100x atmospheric surface pressure
• Enough to compress seawater by 4.96% (water is nearly incompressible — this number is huge)

Human bodies can't survive this. But some species thrive in it.

The four descents

Only four crewed missions have reached Challenger Deep:

• 1960: Bathyscaphe Trieste (Jacques Piccard, Don Walsh)
• 2012: Deepsea Challenger (James Cameron)
• 2019: DSV Limiting Factor (Victor Vescovo)
• 2020+: Multiple additional Limiting Factor dives, including the first woman (Kathryn Sullivan)

James Cameron's solo dive filmed 3 hours of footage. The Trieste managed only 20 minutes before stirred sediment forced an ascent.

What lives there

The hadal zone (below 6,000m) hosts:

• Mariana snailfish — a pink, translucent fish found at 8,178m, the deepest-living vertebrate
• Amphipods — crustaceans that scavenge everything that sinks
• Xenophyophores — single-celled giants up to 10 cm across
• Microbes that thrive at near-freezing temperatures and crushing pressure

Every trench dive finds new species. 76% of deep-sea animals are bioluminescent — but in Challenger Deep, there's nothing to flash at, so bioluminescence fades.

Temperature and light

Temperature: 1–4°C. Pressure keeps water from freezing despite the cold.

Light: zero sunlight reaches below 1,000m. By the time you're at 10,000m, the only light is bioluminescent, and there's barely any of that.

Human pollution has already made it there

A 2018 expedition recovered plastic bags, candy wrappers, and beer cans from Challenger Deep. Amphipods in the trench tested positive for microplastics and radioactive carbon-14 from 1950s nuclear tests.

Humanity's trash reached the bottom before most humans did. See how many species are on Earth for the broader marine biodiversity picture.

Why we haven't mapped more of it

Sonar is slow and expensive at depth. As of 2026, only ~25% of the seafloor has been mapped at high resolution. We have higher-res maps of Mars than of Earth's ocean.

Ships traversing the ocean surface can map 100 km wide per pass. At current pace, full mapping won't complete until ~2035 under the Seabed 2030 initiative.

Is there a deeper place?

Not on Earth. Challenger Deep is the lowest. The next-deepest (Horizon Deep in the Tonga Trench) is 10,823m — 112m shallower.

On other worlds? Hypothetical ocean worlds like Enceladus and Europa have under-ice oceans estimated at 50–150 km deep. If we ever drill through the ice shell, those will shatter every Earth record.

Why trenches matter for climate

The deep ocean absorbs heat and carbon from the surface. Trench water circulates on 1,000+ year timescales. Carbon sinking into the hadal zone is effectively sequestered for centuries.

If deep ocean circulation slows (as some climate models predict), that carbon buffer weakens — and surface temperatures accelerate.

For more extreme-physics scenarios, see what if you could shrink to ant size or how do tsunamis form.