An Australian cave-diver who died last year after becoming separated from his two buddies had fully functioning equipment and the cause of his death remains a mystery, according to a just-completed investigation by the Cave Divers Association of Australia (CDAA).
Gary Gibson, 65, an experienced cave-diver from Victoria, died during an incident in Tank Cave, near Tantanoola in South Australia, in late November, 2025, as reported on Divernet. He was said to have completed as many as 70 previous dives in the system.
After Gibson’s companions had noticed his absence they had proceeded to a pre-determined meeting point and, when he failed to show up, had retraced their route to find him unresponsive, according to the CDAA internal report as reported by ABC News.
South Australia Police (SAPOL) subsequently initiated a two-day recovery operation involving its Water Operations Unit divers assisted by specialist cave-divers.
‘Sometimes things are a mystery’
The report found no evidence that Gibson’s dive-gear had malfunctioned, and his gas levels had been sufficient to complete the planned dive. There had been no indication of a rock collapse or that Gibson had become stuck in a constricted passage, and no unusual cave conditions were identified.
The CDAA said it had no evidence of a medical or other non-equipment-related cause of death, but considered that Gibson was likely already dead by the time the others found him, possibly following a period of high stress or exertion.
The investigation concluded that CDAA safety rules and protocols had been adhered to by all the divers involved. The association’s national director Grant Pearce told ABC News: “We could only conclude that there may have been some other health incident that would have potentially occurred, but we’re not aware of what that is… So sometimes things are a mystery and this is one of those.”
Following the incident both the CDAA and SAPOL had indicated that there were no broader safety concerns about the Tank Cave site. Together with associated system Green Waterhole, it contains some 10km of intersecting passages, making it by far the longest underwater cave system in the state and the second-longest in Australia.
SAPOL has yet to complete its own official report into the fatality for the coroner.
