- Constantin Popovici, Rhiannan Iffland
- 120 metre(s)
- Romania (Turda)
The deepest water under the earth's surface into which a dive has been performed is 120 m (393 ft), achieved by Rhiannan Iffland (Australia) and Constantin Popovici (Romania) who dived from a 20 m platform into an underground lake in the Salina Turda salt mine in Romania, on 14 October 2020.
The salt concentration of the water in the mine makes it around 17% more dense than seawater, meaning the divers decelerated from 85 km/h to 0 in almost twice the usual speed. While most dives will descend to around 5 m below the surface, these dives only reached 2.5 m.
The Turda mine is one of the oldest salt mines in the world. After ceasing salt mining operations in 1932, the location is now one of Romani's most popular tourist destinations with a reported 700,000 annual visitors.