The death of a cave diver in Tank Cave near Tantanoola has shocked the close-knit cave diving community around the world and comes as the third death in the South East from the unique sport in two-years.

A 40-year-old father and experienced cave diver from Doncaster, Victoria was diving inside the cave with his buddy like they had done many times before at the same site, but failed to resurface from the dive.

He was reported missing by his buddy who was a close friend, and the body was retrieved an hour later 50-metres from the entrance to the cave.

Superintendent Trevor Twilley said relatives were notified on the evening of the incident which was now left to the coroner.

"Most of the equipment has been retrieved along with the body to prepare an examination for the coroner," he said.

Both men had over 10-years cave diving experience and held the highest certificates issued by the Cave Divers Association Australia (CDAA).

National Director of CDAA John Vanderleest said there was nothing unusual about yesterday's dive which could have foreseen the tragedy.

"Both men would have done the kind of diving that they would have done at that same location many, many times before.

"To have three deaths in two years is a shock and a complete anomaly to how the sport usually operates," he said.

Tank Cave requires the highest training and experience level before entering the cave which differs from others in the area, said Vanderleest.

"It is a unique geological feature in comparison to the other caves.

"It's a very extensive system, there's more than six-kilometres of underwater passage," he said.

Despite its complexity, he insisted there were no more risks involved than with other adventure sports.

"The risks are well calculated and we spend a lot of time training and preparing for every dive.

"When any person dies cave diving anywhere around the world, the entire community will be watching and waiting to see exactly what happened and modify procedures," he said.

One of Australia's most renowned and experienced cave divers Agnes Milowka died in the same underwater passages of Tank Cave in February earlier this year.