The maximum depth a manned submersible has reached is 10,928 meters (35,853 feet) below the ocean surface, located in the Challenger Deep within the Mariana Trench in the Western Pacific Ocean. This achievement requires a specialized vessel, known as a manned submersible, distinct from uncrewed remotely operated vehicles (ROVs). This extreme depth is part of the hadal zone, a region of the ocean floor deeper than 6,000 meters.
The World Record Dive
The modern record was set in April 2019 by American explorer Victor Vescovo, piloting the two-person submersible DSV Limiting Factor. The precise depth recorded for this solo descent was 10,928 meters in the Eastern Pool of the Challenger Deep. This dive surpassed the historical record and marked the first time a crewed vessel had reached the deepest point of the ocean more than once.
Vescovo’s expedition was part of a larger project to reach the deepest point in all five of the world’s oceans. The depth measurement was confirmed using multiple pressure sensors. This achievement is the current benchmark for human descent into the deepest known part of the Earth’s oceans.
A History of Reaching the Abyss
The first successful manned dive to the Challenger Deep occurred decades earlier on January 23, 1960. The bathyscaphe Trieste, manned by U.S. Navy Lieutenant Don Walsh and Swiss oceanographer Jacques Piccard, reached a depth of approximately 10,916 meters. This achievement stood unchallenged for over half a century and proved that life could exist at such crushing pressures.
Filmmaker James Cameron completed the first solo dive in 2012 aboard his submersible, the Deepsea Challenger. Cameron reached a depth of 10,908 meters, collecting scientific data and samples. The DSV Limiting Factor began making repeated dives in 2019, carrying other explorers and scientists, which significantly increased the number of people who have visited this remote location.
The Technology of Extreme Depth
The primary engineering challenge of reaching the hadal zone is withstanding the immense hydrostatic pressure, which exceeds 1,100 times the atmospheric pressure at sea level. The DSV Limiting Factor addressed this with a pressure hull constructed from a single piece of 90-millimeter-thick titanium alloy. The sphere was machined to 99.933% spherical precision, since a perfectly round shape is the strongest configuration for even pressure distribution.
The submersible utilizes syntactic foam, a specialized material composed of glass microspheres suspended in resin, to provide buoyancy. This foam is strong enough to resist the pressure while remaining lightweight to allow the vessel to ascend. Observation ports, or viewports, are made from thick acrylic and are kept small to minimize structural weakness. The entire vessel is designed to be commercially certified for repeated trips to full ocean depth.
Why Explore the Deepest Points?
Biological Adaptation
Exploration of the deepest trenches offers unique scientific opportunities to study life that has adapted to the most extreme conditions on Earth. These missions study the specialized organisms of the hadal zone, such as the gelatinous hadal snailfish and giant amphipods, which possess unique biological mechanisms to survive the intense pressure. For example, some deep-sea fish accumulate a molecule called trimethylamine N-oxide (TMAO) to counteract the pressure’s effect on their cellular proteins.
Operational Advantages and Geology
Manned dives allow for real-time decision-making, which is an advantage over remotely operated vehicles for complex sampling and geological surveying. Scientists can map the trench floor, often divided into distinct basins or “pools,” using advanced sonar technology. The geological data collected helps researchers better understand the process of plate tectonics, which creates these deep ocean features.