Shirley explained that most world records for diving are what he calls "soap on a rope," -- where divers descend quickly and come right back up again.
But Shaw dove nearly 900 feet, and he attempted a few minutes of unprecedented exploration at the bottom.
"Nobody swims at depth," said Van Schaik. "It's just not done. They'll say you are stupid to swim at depth. But this was proper exploration it was brand new."
When Shaw reached 800 feet, the air mixture in his air tanks began to produce narcosis --what divers call "rapture of the deep."
"It's the effect of the nitrogen in the air that you breathe," said Van Schaik. "And it basically is equivalent to being drunk. So you lose your ability to mentally process and you lose your coordination."
At 876 feet, Shaw reached the cave floor, and did something no deep cave diver has ever done before: he moved away from his main line, cautiously exploring a previously unseen world, where he discovered something he did not expect. It was the body of Deon Dreyer.
"When I discovered Deon, he was lying on his back," said Shaw. "Hand flat, with his arms floating, due to the buoyancy of his wet suit that he was wearing. He still had his mask in place, but the body, part of the body that I could see, had no flesh on it."
Unable to pry the body from the silt, Shaw marked its location with a feeder line, and began a lonely, slow journey back to the top, carrying with him the strange news of his discovery.
After 10 hours underwater, Shaw emerged from Bushman's Hole. He was hardly out of his wet suit when he passed news of the discovery to Deon Dryer's parents, Theo and Marie.
Theo Dryer said that at that moment he was shocked. "It takes a while to sink in. … it's unreal."
Shaw then made an amazing proposition: He offered to go back down and try to bring back Deon Dryer's body.
"I'd come to accept that Deon would never be recovered," Theo Dryer said. "So you get comfortable with the idea. Now all of a sudden, they offer… to recover Deon…[and] there's doubt. Should I leave him there? He's happy there. Or should we recover? But then, yes, we went for the recovery."
Van Schaik said that Shaw and Shirley were the perfect team to attempt the rescue. "They created the perfect team. I think Dave had the drive and the ambition, and Don had the know-how and expertise and his own ambition. Um, but together they were able to… you know, to conquer this."
Shaw and Shirley were attempting the deepest underwater body recovery in history, and South African film producer Gordon Hiles thought it would be a good opportunity for a one-of-a-kind documentary film.
Hiles said that "the number of people who have dived deeper than 250 meters, that, that number is smaller than the amount of people who have actually walked on the moon."
In the weeks after the discovery of Deon Dreyer's body, events moved swiftly. Shaw and Shirley developed a complex dive plan that would require as many as nine different divers working at varying depths. The big question was how to bring the body to the surface.
"The best response I got was, there could be some soft tissue still but mainly [it will] be a skeleton," said Shirley. "And because of that, we were worried about the body falling apart literally, as it was coming up, and that's where the bag idea came from…"
Ann Shaw, Dave's wife, sewed a body bag that would be used to carry Deon Dryer's body.