Boesmansgat, also known in English as "Bushman's Hole", is believed to be the third-deepest submerged freshwater cave (or sinkhole) in the world, approximately 270 metres deep. It is located in the Northern Cape province of South Africa, and is where famed deep cave diver Dave Shaw died on January 8, 2005 while recovering the body of an amateur diver, Deon Dreyer, who had drowned while diving with friends ten years earlier. Dreyer's remains were located at a depth of over 800 feet, and Shaw died while expending considerable effort as he attempted to place the body in a body bag.

Both bodies floated to the surface on January 12, much to the surprise of the recovery team. Details of this event can be found at Outside Online article. ^*

Caves of South Africa | Geography of South Africa