June 15, 2006 -- "Nightline" joined forces with writer Tim Zimmerman and filmmaker Gordon Hiles, who documented an ambitious dive to one of the world's deepest, most dangerous underwater caves.
In the northern cape region of South Africa, near the Kalahari desert, is Bushman's Hole -- the third deepest cave in the world.
At least 927 feet deep, it might take a diver 10 minutes to get to the bottom but at least 10 hours to return to the surface. Even the most experienced diver takes his life into his hands when he tries to reach the bottom.
In 1994, 20-year-old Deon Dreyer descended into Bushman's Hole with 200 successful dives to his name. But this time, he apparently blacked out and was never heard from again.
"Everyone diving in Bushman's knew about Deon Dreyer. His parents had put a plaque commemorating his death above the hole," said Zimmerman, who chronicled the story of Bushman's Hole for the August issue of Outside Magazine.
Ten years later, Dave Shaw, an Australian pilot and experienced deep-water diver, went to Dreyer's parents and volunteered to recover the body.
"Dave felt very connected to Deon," says his close friend Don Shirley, "So it was like a personal thing that he should bring him back."
The plan quickly grew into a complex endeavor. It would take seven support divers, dozens of gas cylinders and a staggering amount of equipment to pull it off. While it was straightforward on paper, everyone involved knew it would be extremely dangerous. Only seven people, including Shaw, had ever been deeper than 820 feet and three of them had died.
Shaw dived into Bushman's hole wearing a special video camera mounted on his helmet as he descended into the underwater cave.