While thousands have summited Mount Everest, the planet’s highest peak, fewer than 30 people have reached the ocean’s deepest point. That location, known as the Mariana Trench, lies hidden in darkness more than 7 miles (11 kilometers) beneath the surface. The deepest point is 36,070 feet (10,994 meters) below sea level.
What is the Mariana Trench?
The Mariana Trench is the deepest oceanic trench on Earth. Located in the western Pacific Ocean, it stretches roughly 1,580 miles (2,550 kilometers) in length and averages about 43 miles (69 kilometers) wide. The trench sits east of the Mariana Islands, around 200 miles (322 kilometers) southwest of Guam.
Within the trench, the deepest region, known as the Challenger Deep, plunges an incredible 36,070 feet (10,994 meters). To put this into perspective, if Mount Everest (29,029 feet or 8,848 meters) were submerged into the trench, its summit would still remain about 1.3 miles (2 kilometers) underwater!
How Did the Mariana Trench Form?
This massive underwater canyon is the result of subduction—a geological process where two of Earth’s tectonic plates collide. Specifically, the Pacific Plate is moving westward and diving beneath the smaller Mariana Plate. As the Pacific Plate subducts, it bends and creates the deep, crescent-shaped trench.
This subduction zone is active, causing frequent earthquakes. Studying the trench helps geologists understand seismic activity and tsunamis in the Pacific Rim.
Studying the Mariana Trench
Human curiosity about the Mariana Trench began during the 1870s. In 1875, the British ship HMS Challenger made the first measurement of its depth, recording roughly five miles (8 kilometers) using a weighted rope.
Nearly a century later, in 1951, HMS Challenger II employed advanced echo-sounding technology, discovering the true depth was nearly 7 miles (11 kilometers). This deepest spot became known as the Challenger Deep in tribute to these pioneering expeditions.
In 2009, the Mariana Trench Marine National Monument was established by U.S. President George W. Bush. The monument was created to preserve the region’s unique geology and fragile ecosystems from deep-sea mining and unregulated fishing. It is managed by the U.S. Fish and Wildlife Service and NOAA, in coordination with local governments. Access is restricted, and research permits are required.
Who Has Reached the Bottom?
To date, fewer than 30 people have reached Challenger Deep, making it far more exclusive than Everest’s summit which has been reached by over 7,200 people as of December 2024.
The first successful descent took place in 1960, when Swiss oceanographer Jacques Piccard and U.S. Navy Lieutenant Don Walsh descended aboard the bathyscaphe Trieste. Their five-hour journey took them to the trench’s bottom, where they spent approximately 20 minutes.
Decades later, Canadian filmmaker James Cameron reached Challenger Deep alone in 2012, filming and sampling organisms for scientific study. More recently, American explorer Victor Vescovo completed multiple dives between 2019 and 2021.
Sadly, human impact reaches even these remote depths. On recent dives, researchers have discovered discarded plastics and bottles at the trench bottom.
Challenges of Deep-Sea Diving vs. Mountain Climbing
Descending into the Mariana Trench isn’t like scuba diving or even piloting a submarine. At 36,000 feet (10,973 meters) below the surface, the pressure reaches 16,000 pounds per square inch—over 1,000 times the air pressure at sea level. Any conventional sub would be instantly crushed. Only specially engineered vessels, like bathyscaphes and deep submergence vehicles (DSVs), can survive the descent. These crafts have thick titanium or syntactic foam hulls designed to resist deformation under extreme pressure.
Inside, pilots face a cramped, cold, and silent environment. Temperatures near freezing can affect electronics, hydraulics, and the mental clarity of the operator. Heat from onboard systems must be retained without overheating critical instruments. Life-support systems must recycle air and manage CO₂ buildup. Visibility is almost zero without artificial lighting. Communications with the surface are slow and often unreliable due to depth and seawater interference.
There’s no pressure suit that can take a human to these depths. Exposed diving is impossible. Every descent to Challenger Deep requires a pressurized capsule, hardened components, and redundancies for power, oxygen, and ascent. A single mechanical failure at depth means death. Rescue is impossible.
By contrast, mountain climbers deal with physiological decay from lack of oxygen. At extreme altitudes above 26,000 feet (7,900 meters), known as the “death zone,” oxygen saturation drops so low that the human body begins shutting down. Acclimatization takes weeks. Altitude illness, frostbite, pulmonary and cerebral edema are constant threats. Unlike diving, climbers must exert themselves at a time when their muscles are starved of oxygen.
Both environments are lethal in different ways. On a mountain, it’s your body that gives out. In the deep, it’s your equipment. One tests human physiology while the other tests human engineering.
Life Deep in the Mariana Trench
Early doubts surrounded the possibility of life at such depths, given the immense pressure and lack of light. However, scientists have discovered remarkable organisms adapted to these conditions.
Creatures like amphipods—tiny shrimp-like scavengers—and translucent sea cucumbers (holothurians) thrive at Challenger Deep. Perhaps most extraordinary is the snailfish, found swimming at depths of nearly 27,000 feet (8,230 meters), whose cartilage-based skeleton withstands crushing pressures.
Scientists also study deep-ocean microbes. Their extreme adaptations may unlock advances in biotechnology and medicine, potentially offering insights into life’s origins on Earth.
Mariana Trench FAQs
Is the Mariana Trench the deepest ocean location?
Yes, it is the deepest known oceanic trench on Earth.
What’s the deepest point of the Mariana Trench?
Challenger Deep, at approximately 36,070 feet (10,994 meters).
How does it compare to the height of Mount Everest?
Mount Everest is 29,029 feet (8,848 meters) tall. Everest would fit completely submerged in the Mariana Trench and still have over a mile (1.6 kilometers) of water above it.
What’s the temperature and pressure at Challenger Deep?
The temperature at Challenger Deep hovers just above freezing, typically around 34 to 39°F (1 to 4°C). The pressure is over 16,000 pounds per square inch .
Have many people reached Challenger Deep?
Fewer than 30 people have successfully descended.
Is the Titanic near the Mariana Trench?
No. Titanic sank in the North Atlantic Ocean, approximately 12,500 feet (3,800 meters) deep, far shallower than the Mariana Trench.
What are some other notable trenches?
Tonga Trench – South Pacific Ocean
- Depth: ~35,702 feet (10,882 meters)
- Location: Northeast of New Zealand
- Deepest trench in the Southern Hemisphere
Philippine Trench – Western Pacific Ocean
- Depth: ~34,580 feet (10,540 meters)
- Location: East of the Philippines
- Also called the Mindanao Trench
Kuril–Kamchatka Trench – Northwest Pacific Ocean
- Depth: ~34,449 feet (10,500 meters)
- Location: Off the coast of Russia’s Kamchatka Peninsula and Kuril Islands
- Site of major seismic activity
Kermadec Trench – South Pacific Ocean
- Depth: ~32,963 feet (10,045 meters)
- Location: North of New Zealand
- Continuation of the Tonga Trench system
Izu–Bonin Trench – Western Pacific Ocean
- Depth: ~32,618 feet (9,939 meters)
- Location: South of Japan
- Part of the Izu–Bonin–Mariana Arc system
Peru–Chile Trench (Atacama Trench) – Southeast Pacific Ocean
- Associated with frequent megathrust earthquakes and tsunamis
- Depth: ~26,460 feet (8,065 meters)
- Location: Off the west coast of South America
