BushMan´s HoLe: South Africa

Boesmansgat or Bushman's Hole, located in Mount Carmel Game Farm in the Northern Cape, is the third world's deepest submerged freshwater cave or sinkhole.
Its precise depth size still needs to be verified... 
The cave is located at an altitude of 5000 feet (1550 m) above sea level
On the 24 of November, 2004 Verna van Schaik established the existing Guinness Woman's World Record for the deepest dive: 221 meters (725ft).
Nuno Gomes a South African scuba diver holds the official current Guinness World Record for the deepest cave dive in Bushman´s cave to a depth of 927 feet (282.6 m), in 1996. 
Two scuba divers have died there: 
1994 Deon Dreyer a South African diver helping set up Nuno Gomes´ Guinness World Record dive. 
2005 David Shaw, an Australian scuba diver who found in 2004 Dreyer´s missing body and died trying to recover it.