Despite the best efforts of seven volunteer lifesavers, an off-duty paramedic and a helicopter crew, an older male diver was unable to be revived on the South Coast on Wednesday.
In the aftermath, Surf Life Saving NSW warned the public to enjoy water activities - but not alone.
The Westpac Life Saver Rescue Helicopter (Lifesaver 23) was sent to search for the man, believed to be in his 70s, at Denhams Beach, south of Batemans Bay, at 2.24pm.
Far South Coast Surf Lifesaving duty officer, Anthony Bellette, responded to the missing-person alert with on-call volunteers from the Batemans Bay club.
He happened to be in the right place at the right time and he was an absolute asset to work with
Police also joined the search.
At 3.05pm, Lifesaver 23 located the man floating unconscious and not breathing in the water at Sunshine Bay.
The crew winched the man aboard and flew him to Sunshine Bay beach.
Paramedics and volunteer lifesavers continued first aid and CPR on the beach.
Mr Bellette said an off-duty paramedic was among the first at the scene.
"He happened to be in the right place at the right time and he was an absolute asset to work with," he said.
At 3.15pm, NSW Ambulance arrived at the scene.
Efforts to revive the man were unsuccessful and crews were stood down at 3.17pm.
... always have someone with you when you're diving or snorkeling - it's best not to go on your own
On behalf of Batemans Bay's lifesavers at the scene, Mr Bellette expressed sympathy for the diver's partner and family. The couple was understood to have been holidaying in the area.
"We feel for the gentleman and his partner who were supposed to be there having a good time," Mr Bellette said.
The tragic outcome was tough on those who worked so hard to save him.
"Something like this is always hard for the team, but all the training helps," Mr Bellette said.
The tragedy occurred despite calm conditions.
"The conditions were amazing, it was a beautiful day and the water's visibility was great for diving," Mr Bellette said.
Surf Life Saving NSW spokeswoman Donna Wishart said the cause of death was unknown.
"It could be that this gentleman had a medical episode which may not be related to him being in the water," she said.
"It could be an existing medical condition that caused it."
Ms Wishart shared a timely safety reminder for snorkelers and divers.
"With any water activity we recommend having the right gear and to make sure it is reliable," she said.
"Also, to check the weather; especially tides, particularly around rock platforms or rocky outcrops.
"It's also recommended you always have someone with you when you're diving or snorkeling - it's best not to go on your own. Always tell someone where you are going and the time you're expected back," Ms Wishart said.