Visitors to a popular dive spot within the Jervis Bay Marine Park spent more than 40 years swimming over and around an unexploded bomb.
The 230kg Mark 82 general purpose bomb disappeared into the water in 1982 and came to rest near the rock formation known as the Drum and Drumsticks at Jervis Bay's entrance.
It was only recently spotted by a recreational diver who reported it to police, and also provided GPS coordinates, photos and descriptions of the area.
Details the diver provided helped the navy clearance divers who were called in to deal with the unexploded bomb.
Officer in charge of maritime explosive ordnance disposal, Chief Petty Officer Joshua Drennan, said it was a sensitive operation because of the wildlife in the area and the rock formation's popularity as a recreational dive site.
He said the dive team had to overcome a number of challenges to locate the bomb, which was eventually found just 30 metres from a thriving seal community.
"The GPS locations that we had changed so we had to rotate through nearly our whole dive team," CPO Drennan said.
"Roughly 11 divers went in the water, two divers at a time, to try to locate it.
"We mainly used visual search because sonar is very difficult in among the rocks."
Once the dive team had located the bomb, it was towed to a safe location about 3km from shore and detonated.
"Exactly where the item was located was deep in the marine park, so we had to go for a very long tow to remove that item outside of the marine park to make sure we weren't going to damage any of the marine life," CPO Drennan said.
"It's one of the most popular dive spots down here so we need to make sure it's clear for boating, people in the water and also marine life."
During the operation police maintained a cordon in the area and monitored local marine traffic to help ensure safety.
The navy's director general of maritime operations, Commodore Michael Harris, congratulated the divers on the successful operation.
"The team has achieved an excellent outcome, safely removing this ordnance from this popular and environmentally sensitive dive site despite difficult sea conditions, all the while protecting marine wildlife and public safety," Commodore Harris said.
"Their commitment to maintaining safety and protecting the environment throughout reflects the importance the Royal Australian Navy places on safety and environmental protection."
The Sydney-based Clearance Diving Team One is one of two full-time navy dive teams comprised of specialist divers capable of overt and clandestine reconnaissance, mine clearance, underwater damage repair, explosive ordnance disposal and providing support to special forces.
