The Challenger Deep, the deepest known point on Earth, represents one of the planet’s last true frontiers for human exploration. This remote location, hidden beneath the waves of the Pacific Ocean, is far more difficult to reach than outer space. Fewer individuals have successfully completed a descent to the seafloor than the total number of people who have walked on the moon. This comparison highlights the immense challenge of reaching the ocean’s bottom.
The Definitive Count of Human Descents
The total number of individuals who have successfully reached the Challenger Deep is approximately 27 people, as of early 2024. This count is subject to change as modern expeditions continue to operate. For over fifty years, the number of successful human descents remained in the single digits.
The count dramatically increased starting in 2019 due to the introduction of a new, commercially available submersible designed for repeated full-ocean-depth missions. It is important to distinguish between the total number of missions and the number of unique individuals. The earliest and most recent missions were crewed by two people, while the 2012 expedition was a solo dive.
Defining the Mariana Trench and Challenger Deep
The Challenger Deep is the deepest section within the larger Mariana Trench, not a standalone feature. This trench is a crescent-shaped scar located in the Western Pacific Ocean, east of the Mariana Islands near Guam. It extends for about 2,550 kilometers (1,580 miles) and marks a subduction zone where the Pacific Plate slides beneath the Mariana Plate.
Modern estimates place the precise depth of the Challenger Deep at approximately 10,935 meters (35,876 feet) below sea level. If Mount Everest were placed at the bottom of the trench, its peak would still be submerged by more than a mile of water. This extreme vertical distance creates immense challenges for exploration.
The water pressure at this depth is the most significant barrier to human presence. It exceeds 1,000 times the standard atmospheric pressure found at sea level, reaching about 15,750 pounds per square inch. This force would instantly crush most conventional vessels. Submersibles designed for this environment must feature incredibly thick, spherical pressure hulls to withstand this pressure.
Notable Expeditions and Historic Submersibles
Exploration began with the 1960 descent aboard the bathyscaphe Trieste. This mission was crewed by Swiss oceanographer Jacques Piccard and U.S. Navy Lieutenant Don Walsh, marking the first time humans reached the ocean floor. Their descent took nearly five hours, and they spent about twenty minutes on the seafloor before ascending.
The next successful manned mission occurred 52 years later in 2012. Filmmaker and explorer James Cameron made a solo dive in the Deepsea Challenger, a custom-built submersible. He reached a depth of 10,908 meters (35,787 feet), becoming the third person to visit the Challenger Deep.
The modern era began in 2019 with the Five Deeps Expedition, led by American explorer Victor Vescovo. Piloting the two-person submersible Limiting Factor, Vescovo completed multiple dives and quickly became the person with the most visits. The vessel’s capability for repeated dives opened the door for many others to visit the location.
The Limiting Factor’s design allowed several explorers to join the group, including Kelly Walsh, the son of Don Walsh. It also carried the first two women to visit the deepest point: astronaut Kathryn Sullivan and adventurer Vanessa O’Brien. The regularity of these recent dives has rapidly expanded the number of people who have witnessed this abyssal plain.