The Deepest Points in the Ocean

The deepest confirmed point in any ocean is Challenger Deep, a slot-shaped basin at the southern end of the Mariana Trench in the western Pacific, roughly 10,935 meters (35,876 feet) below the surface (NOAA Ocean Exploration). Only four crewed descents have ever reached it, the most recent led by Victor Vescovo's Five Deeps Expedition in 2019. This piece walks through how that number was actually measured, what a thousand atmospheres of pressure does to a submersible hull, and which animals have adapted to live down there permanently.

What "deepest point" actually means

Hadal zone — the ocean depth band below about 6,000 meters (19,700 feet), named after Hades, the Greek underworld. It is the deepest of the ocean's named depth layers, sitting below the abyssal zone and confined almost entirely to trenches rather than open seafloor. Most of the ocean never gets this deep; the average depth of all the world's oceans is about 3,682 meters (12,080 feet), according to the National Oceanic and Atmospheric Administration. The hadal zone exists because of a specific geological accident, not because the seafloor gradually slopes downward everywhere.

That accident is subduction. Where one tectonic plate dives beneath another, it drags the seafloor down into a long, narrow trench before the plate continues its descent into the mantle. Nearly every hadal trench on Earth traces the edge of the Pacific Ring of Fire, the horseshoe of subduction zones that also produces most of the planet's earthquakes and volcanoes. This is why "deepest point in the ocean" is really a story about plate tectonics before it is a story about water.

It also explains why the deepest points cluster geographically instead of being scattered randomly across the seafloor. Trenches are linear features, often hundreds to thousands of kilometers long, with the single deepest spot forming wherever the subducting plate's angle and the accumulated sediment happen to align. Challenger Deep itself is not a single hole; it is one of three sub-basins (Eastern, Central, and Western Pool) inside a trench that runs roughly 2,550 kilometers (1,580 miles) end to end.

The pressure at Challenger Deep is roughly 1,086 times normal sea-level atmospheric pressure — equivalent to the weight of about 50 jumbo jets pressing on a single point (NOAA Ocean Exploration).

The world's deepest ocean trenches, ranked

Depth measurements for hadal trenches have shifted over the decades as sonar technology improved, and different research groups still report slightly different figures for the same location depending on survey year and methodology. The table below uses the most widely cited modern figures, primarily from the Five Deeps Expedition's 2019–2021 sonar mapping and NOAA's published depth records.

Trench	Ocean	Deepest Point	Approx. Depth	Source Expedition
Mariana Trench	Pacific	Challenger Deep	10,935 m (35,876 ft)	Five Deeps Expedition, 2019
Tonga Trench	Pacific	Horizon Deep	10,823 m (35,509 ft)	Five Deeps Expedition, 2019
Philippine Trench	Pacific	Emden Deep	10,540 m (34,580 ft)	Five Deeps Expedition, 2019
Kermadec Trench	Pacific	Scholl Deep	10,047 m (32,963 ft)	NOAA / GEBCO
Kuril–Kamchatka Trench	Pacific	(unnamed)	9,604 m (31,509 ft)	GEBCO
Izu-Ogasawara Trench	Pacific	(unnamed)	9,780 m (32,087 ft)	GEBCO
Puerto Rico Trench	Atlantic	Milwaukee Deep	8,376 m (27,480 ft)	NOAA
South Sandwich Trench	Atlantic/Southern	Meteor Deep	8,265 m (27,116 ft)	Five Deeps Expedition, 2019
Java Trench	Indian	(unnamed)	7,290 m (23,917 ft)	GEBCO
Molloy Deep	Arctic	Molloy Hole	5,550 m (18,209 ft)	Five Deeps Expedition, 2019

Nine of the ten deepest points on the planet sit inside the Pacific's Ring of Fire; the Puerto Rico Trench is the deepest point in the entire Atlantic Ocean, and the Molloy Deep is the deepest point in the Arctic Ocean, less than half the depth of Challenger Deep.

The gap between the top three entries is worth pausing on. Challenger Deep beats the Tonga Trench's Horizon Deep by roughly 112 meters (367 feet) — a difference smaller than the height of many skyscrapers, yet it is why one trench earns headlines and the other stays obscure. The margin illustrates how close some of these measurements are to each other, and how much precision modern sonar and pressure sensors need to resolve a genuine winner.

Measuring Challenger Deep: four dives across 60 years

Confirming the depth of a spot at the bottom of the Pacific is harder than it sounds, because sound itself is the primary measuring tool, and sound behaves differently depending on water temperature, salinity, and pressure at every meter of the descent. Getting an accurate number required both better sonar and, eventually, people willing to physically go down and check.

The 1960 Trieste dive

On January 23, 1960, U.S. Navy Lieutenant Don Walsh and Swiss engineer Jacques Piccard rode the bathyscaphe Trieste to the bottom of Challenger Deep, becoming the first humans to reach it. The descent took nearly five hours, and the pair spent only about 20 minutes on the bottom before a cracked outer window pane forced an early return. Their depth gauge read approximately 10,916 meters (35,814 feet), a figure later revised as sonar technology improved (Woods Hole Oceanographic Institution).

The 2012 Deepsea Challenger dive

No human returned to the bottom of Challenger Deep for 52 years. On March 26, 2012, filmmaker and explorer James Cameron piloted the Deepsea Challenger, a vertical torpedo-shaped submersible he helped design, on a solo dive to approximately 10,908 meters (35,787 feet). It was the first solo descent to the deepest point on Earth and the first to bring back high-resolution video and rock and biological samples from the Challenger Deep floor, in partnership with the National Geographic Society.

The 2019–2021 Five Deeps Expedition

Between 2019 and 2021, private equity investor and former naval officer Victor Vescovo led the Five Deeps Expedition, an effort to reach the deepest point of all five oceans in a single continuous campaign using the submersible Limiting Factor. Vescovo's team made multiple dives to Challenger Deep, mapped the trench with high-resolution multibeam sonar carried aboard the support ship Pressure Drop, and produced the most detailed bathymetric survey of the trench to date. Their sonar data, later refined and published with additional analysis through 2021, set the depth at approximately 10,935 meters (35,876 feet), with the Eastern Pool identified as the true deepest sub-basin (Five Deeps Expedition; NOAA Ocean Exploration).

Each expedition's number differs by only tens of meters from the others, but those differences matter for verifying which basin is truly deepest and for calibrating the sonar systems used across the rest of the world's trenches. The consistent trend across sixty years of measurement is that the number has settled, not swung wildly — modern estimates cluster within about 30 meters (98 feet) of each other, a strong sign the figure is close to its true value.

The physics of a thousand atmospheres

Water pressure increases by roughly 1 atmosphere (about 101 kilopascals) for every 10 meters (33 feet) of depth. At Challenger Deep's roughly 10,935 meters, that works out to over 1,000 atmospheres, or more than 1,086 times the pressure a person feels standing at sea level (NOAA Ocean Exploration). Put another way, every square centimeter of a submersible's hull at the bottom of Challenger Deep is bearing a load close to the weight of a small car.

Think of it like the difference between resting a hand flat on a table and having that same hand support the weight of a loaded delivery truck. At the surface, a human body is built to withstand roughly one atmosphere and barely notices it. At Challenger Deep's depth, that same hand-sized patch of skin would need to resist force equivalent to a truck's weight pressing down on it, evenly, from every direction at once. Submersibles built to survive this are not thin-walled vehicles; the Limiting Factor's crew sphere is a solid titanium shell nearly 9 centimeters (3.5 inches) thick, precision-machined to distribute that load evenly rather than let it concentrate on any single weak point.

This uniform, all-directions pressure is also why hadal-zone engineering is closer to submarine spacecraft design than to standard shipbuilding. A dented hull at shallow depth is a cosmetic problem; a microscopic flaw in a hadal submersible's pressure sphere can trigger implosion, because the pressure differential across even a hairline crack is enormous. That is precisely what forced Piccard and Walsh to cut their 1960 dive short — a cracked outer window, not the main pressure sphere, but close enough to end the mission early.

Why does pressure increase with ocean depth?

Water pressure rises with depth because deeper water has to support the combined weight of every layer of water above it. Since water is nearly incompressible, that weight adds up steadily and linearly, roughly one atmosphere per 10 meters (33 feet), rather than leveling off the way atmospheric pressure does with altitude in air.

Life at the bottom of the hadal zone

Despite crushing pressure, near-freezing temperatures around 1–4°C (34–39°F), and total darkness, the hadal zone is not lifeless. Sediment samples and video from the Trieste, Deepsea Challenger, and Five Deeps dives have all documented active biological communities at or near the very bottom of Challenger Deep.

The most visually striking residents are hadal snailfish (family Liparidae), including the species Pseudoliparis swirei, described from specimens collected in the Mariana Trench and confirmed as the deepest-living fish species yet documented, found at depths beyond 8,000 meters (26,000 feet) (Gerringer et al., 2017, published in Zootaxa). Snailfish survive the pressure partly through a biochemical trick: they accumulate a compound called trimethylamine N-oxide (TMAO) in their cells, which stabilizes proteins against the pressure that would otherwise deform them. The deeper the species lives, the more TMAO its tissues carry, a pattern researchers have measured directly across multiple hadal fish species.

Below the depth where fish can survive, the community shifts almost entirely to invertebrates. Giant amphipods — shrimp-like crustaceans that can grow far larger than their shallow-water relatives, a pattern called deep-sea gigantism — have been filmed swarming bait traps lowered into Challenger Deep itself. Xenophyophores, single-celled organisms that can grow to several centimeters across despite being just one cell, carpet parts of the trench floor and were directly observed and sampled during the Five Deeps dives. Microbial mats and sediment-dwelling bacteria round out the ecosystem, feeding on organic material — dead plankton, wood fragments, even plastic debris — that sinks down from the surface over weeks or months, a process oceanographers call marine snow.

James Cameron's 2012 dive brought back mud and rock samples containing more than 100 new microbial species candidates, a reminder that the trench's biology is still being cataloged more than a decade later (National Geographic Society).

None of these organisms are simply "tougher" versions of shallow-water animals. They are built around fundamentally different cell chemistry, in the same way a car engineered for the Arctic uses different fluids and metals than one built for the desert, not just a thicker coat of paint. Enzymes that would fold and stop functioning at 1,000 atmospheres in a surface organism work normally in a hadal snailfish because the underlying protein structure itself is different.

Why plastic and pollution already reach the bottom

The hadal zone's isolation is not the shield it once seemed. Researchers analyzing amphipods collected from the Mariana Trench and other hadal trenches found measurable concentrations of persistent organic pollutants, including PCBs (polychlorinated biphenyls), in the animals' tissue — chemicals banned for industrial use decades ago in most countries (Jamieson et al., 2017, published in Nature Ecology & Evolution). A plastic bag was also documented on camera resting on the floor of Challenger Deep during a 2019 Five Deeps dive, cataloged by the Deep-Sea Debris Database maintained by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC).

This matters because the hadal zone was long assumed to be too remote and too disconnected from surface currents to accumulate human waste in meaningful quantities. Marine snow turns out to be an efficient elevator for pollutants as well as food: contaminants that bind to sinking organic particles near the surface ride those particles all the way down, concentrating in trench sediment over time rather than dispersing. The deepest point on Earth, it turns out, is not a pristine, untouched frontier — it is downstream of everything that happens near the surface, just on a longer delay.

Why Everest has thousands of summiters and Challenger Deep has barely a dozen

The comparison between Earth's highest and lowest points is not just about elevation, it is about access, and the gap is stark. More than 6,000 individual summits of Mount Everest had been recorded by the mid-2020s, with some climbers, most notably Nepali guide Kami Rita Sherpa, reaching the top more than 30 times each across their careers (Nepal Department of Tourism climbing records). Challenger Deep, by contrast, had been visited by only a small handful of individuals across more than a dozen total dives as of the mid-2020s, starting with Piccard and Walsh in 1960 and including Cameron's 2012 solo descent and the multiple dives Victor Vescovo's team completed between 2019 and 2021.

The imbalance comes down to a fundamentally different engineering problem, not a difference in ambition or funding. Climbing Everest is dangerous and expensive, but it is achievable with trained fitness, supplemental oxygen, and guided support; thousands of paying clients have summited using broadly similar, repeatable equipment and routes refined over seven decades since Edmund Hillary and Tenzing Norgay's first ascent in 1953. Reaching Challenger Deep requires a purpose-built vehicle capable of surviving pressure equivalent to the weight of about 50 jumbo jets concentrated on a single point, with a pressure hull that cannot be mass-produced or meaningfully reused off-the-shelf, because each one is a custom-engineered, extensively pressure-tested vessel. There is no "guided tour" infrastructure at the bottom of the Mariana Trench the way there is at Everest base camp, and a single design flaw at hadal depth is catastrophic in a way that a climbing mistake, while often fatal, is not systemic to the vehicle itself.

That gap is closing, slowly. Private ventures, including tourism-oriented submersible operators building on the Limiting Factor's design lineage, have begun offering paid civilian dives to Challenger Deep since the early 2020s, but the price, logistics, and technical risk still put it in a different category entirely from commercial Everest expeditions. For the foreseeable future, standing on the roof of the world will remain a far more common human achievement than sitting on its floor.

Why have so few people visited the deepest point in the ocean compared to the highest point on land?

Reaching Challenger Deep requires a custom-engineered submersible with a pressure hull built to survive roughly 1,086 atmospheres, a vehicle class that cannot be mass-produced the way climbing gear can, while Everest can be climbed with broadly standardized equipment and guided support. That difference in required engineering, not a lack of interest, is why Everest has had thousands of summiters and Challenger Deep has had barely a dozen visits.

Common mistakes and misconceptions

A handful of misunderstandings about ocean depth recur often enough to be worth correcting directly.

• Mount Everest would not "just fit" in Challenger Deep with room to spare. Everest stands about 8,849 meters (29,032 feet) above sea level; Challenger Deep is about 10,935 meters below it. The trench is deeper than Everest is tall, by roughly 2,000 meters (6,600 feet), not by a comfortable margin that leaves the summit poking well above the surface.
• "Deepest ocean" and "deepest trench" are not automatically the same thing everywhere. Challenger Deep happens to be both the deepest point in the Mariana Trench and the deepest point in any ocean on Earth, but that is Pacific-specific; the deepest point in the Atlantic (Milwaukee Deep) and the deepest point in the Arctic (Molloy Deep) are each far shallower than Challenger Deep and belong to entirely different trench systems.
• Submersibles reaching the hadal zone are not simply "stronger" versions of shallow submarines. Military and research submarines that operate at a few hundred meters use very different hull geometry and materials than hadal-rated vehicles, which require spherical (not cylindrical) pressure hulls because a sphere distributes crushing force more evenly than any other shape.
• The deepest point on Earth is not unexplored territory anymore. As of 2021, more than a dozen individual crewed and uncrewed dives have reached Challenger Deep, a sharp change from the 52-year gap between the 1960 and 2012 missions. It remains rare, not never-visited.

The takeaway

Challenger Deep's depth of roughly 10,935 meters is the product of ordinary plate tectonics taken to an extreme, not some special ocean feature. Sixty years of increasingly precise expeditions, from the Trieste's cracked window in 1960 to the Five Deeps Expedition's sonar surveys in 2019–2021, have converged on a consistent number rather than a contested one. What makes the hadal zone worth studying is not just the pressure or the darkness; it is that life adapted to survive both, and that human pollution has already found its way down there too. The deepest point on the planet turns out to be less isolated, and less empty, than its reputation suggests.

FAQ

Q: How deep is the deepest point in the ocean? Challenger Deep, in the Mariana Trench, is the deepest confirmed point in any ocean at approximately 10,935 meters (35,876 feet) below sea level, based on the Five Deeps Expedition's 2019–2021 sonar survey and NOAA's published records.

Q: Who was the first person to reach the deepest point in the ocean? Jacques Piccard and Don Walsh became the first humans to reach Challenger Deep on January 23, 1960, aboard the bathyscaphe Trieste, recording a depth of approximately 10,916 meters (35,814 feet).

Q: Is Challenger Deep deeper than Mount Everest is tall? Yes. Challenger Deep is about 10,935 meters below sea level, while Mount Everest rises about 8,849 meters above it, a difference of roughly 2,000 meters (6,600 feet).

Q: What lives at the bottom of the Mariana Trench? Documented hadal-zone life includes snailfish such as Pseudoliparis swirei, found beyond 8,000 meters and confirmed as the deepest-living fish species known; giant amphipods; single-celled xenophyophores; and sediment bacteria that feed on organic material sinking from the surface.

Q: How much pressure is at the bottom of Challenger Deep? Pressure at Challenger Deep is roughly 1,086 times sea-level atmospheric pressure, or just over 1,000 atmospheres (about 108 megapascals), according to NOAA Ocean Exploration.

Q: Has pollution reached the deepest parts of the ocean? Yes. Studies of amphipods from the Mariana Trench and other hadal trenches found PCB contamination in their tissue, and a plastic bag has been photographed on the floor of Challenger Deep, documented in JAMSTEC's Deep-Sea Debris Database.

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