A 2021 study estimated Challenger Deep’s maximum depth at 10,935 m, with an uncertainty of ±6 m.
The estimate came from submersible transects made in June 2020 and published by Samuel Greenaway, Kathryn Sullivan, and colleagues. Rather than relying only on ship-mounted sonar, the researchers combined acoustic echo sounding with direct pressure measurements from a full-ocean-depth submersible. They also corrected for water-column properties, atmospheric pressure, gravity effects, and changes in sea level.
Challenger Deep is located in the Mariana Trench’s southern end and consists of several adjoining basins. This matters because different surveys can identify different local maxima. Other modern measurements have produced nearby values, including roughly 10,924–10,925 m from sonar mapping and direct-depth estimates around 10,923–10,925 m.
The figure should therefore be understood as a study-specific estimate, not a permanently settled single number. Older reports, including early measurements from the bathyscaphe Trieste and the Japanese ROV Kaikō, gave different depths because instruments, reference levels, and correction methods improved over time.