The Deepest Free Dives

The deepest dive achieved on a single breath is 253.2 metres (831 ft), reached by the Austrian freediver Herbert Nitsch in the No-Limits discipline off Santorini, Greece, in June 2012. In No-Limits, the diver descends on a weighted sled and returns using a lift bag, so the record measures pure depth tolerance rather than swimming.

Nitsch, nicknamed "the deepest man on Earth," suffered decompression sickness on that dive and later recovered. Depth records vary sharply by discipline: in Constant Weight, where the diver swims down and back unaided, the men's record is 132 m (Alexey Molchanov). At these depths the lungs compress to a fraction of their surface volume and the heart rate can fall below 30 beats per minute through the mammalian dive reflex.