Mariana Trench

Stack Mount Everest into the ocean’s deepest point, and its summit would still sit over a mile underwater. Only three crewed dives have ever reached the bottom. This article covers the Mariana Trench, and what it took to get there.

The bathyscaphe Trieste alongside the USS Lewis, over the Mariana Trench, on 23 January 1960 — the day of the first crewed descent to Challenger Deep. U.S. Navy photo, public domain, via Wikimedia Commons.

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WorldGeo0022 · World Geography

The Mariana Trench

Earth’s deepest point, reached by only three crewed dives in history

1875

HMS Challenger Charts It

A British survey ship first measures the trench’s extreme depth, giving Challenger Deep its name.

23 January 1960

Trieste Reaches the Bottom

Don Walsh and Jacques Piccard become the first humans to reach Challenger Deep, spending 20 minutes there.

26 March 2012

James Cameron Dives Solo

Filmmaker James Cameron reaches Challenger Deep alone in DEEPSEA CHALLENGER, exploring for several hours.

Today

Even the Deepest Point Isn’t Untouched

A plastic bag and candy wrappers have both been documented on the floor of Challenger Deep.

Just How Deep Is That?

Challenger Deep runs about 10,935 metres down. Place Mount Everest inside it, and the summit would still sit more than a mile below the ocean’s surface.

Map of the Mariana Trench, in the western Pacific Ocean near the Mariana Islands. Map: wallace, CC BY 2.5, via Wikimedia Commons.

📑 Contents

1The Ocean’s Deepest Point
2First Descents
3Test Yourself
4Life Under Crushing Pressure

The Ocean’s Deepest Point Need to Know

The Mariana Trench lies in the western Pacific Ocean, near the Mariana Islands, northeast of the Philippines.
It’s crescent-shaped, stretching about 2,550 km long and 69 km wide.
Its deepest point is Challenger Deep, at roughly 10,935 metres (35,876 feet) below sea level — the lowest point on Earth’s surface.
The trench formed through subduction. The old, dense Pacific Plate is forced beneath the smaller Mariana Plate, a process that’s been ongoing for over 50 million years.
Pressure at Challenger Deep reaches about 1,086 bar — roughly equivalent to the weight of 1,800 elephants pressing down on a single point.

First Descents Good to Know

The trench takes its name from the HMS Challenger, a British survey ship that first charted its extreme depth in 1875.
On 23 January 1960, U.S. Navy Lieutenant Don Walsh and Swiss oceanographer Jacques Piccard reached Challenger Deep in the bathyscaphe Trieste. They spent just 20 minutes at the bottom.
On 26 March 2012, filmmaker James Cameron became the first person to reach Challenger Deep solo, in the submersible DEEPSEA CHALLENGER. He explored for several hours, far longer than the 1960 dive.
As of 2026, only these three crewed descents to the very bottom have ever been made, though several later expeditions have reached it too.

Test Yourself

Life Under Crushing Pressure Great to Know

Life still survives at these depths. The Mariana snailfish, small, pink, and scaleless, is the top predator around 8,000 metres down — the deepest-living fish known.
Other residents include giant single-celled organisms called xenophyophores, and pale amphipods that scavenge the seafloor.
If Mount Everest were placed inside Challenger Deep, its summit would still sit more than a mile underwater. That’s a scale most people find hard to picture from the surface.
Even this remote a place isn’t free of human impact. A plastic bag was documented on the floor of Challenger Deep in 2019, along with other plastic waste found in the guts of creatures collected there.
The trench’s extreme, alien conditions make it valuable to scientists well beyond oceanography — it’s studied for clues to how life might survive in equally hostile environments elsewhere, including other planets’ oceans.