A 91-year-old woman was found floating face down at the Bogey Hole in Mollymook at 11.15am on Wednesday.
Swimmers noticed the woman floating face-down in the popular swimming hole and brought her to shore where an off-duty lifeguard and a Sydney doctor commenced CPR.
Ambulance paramedics arrived and could not revive the woman.
Emergency services, including Ambulance, NSW Fire and Rescue and life guard attended the scene and the swimming hole was closed while investigations were carried out.
Australian Lifeguard Service south coast coordinator Ken Walsh told the Milton Ulladulla Times the off duty lifeguard contacted personnel who were on patrol 100 metres away at South Mollymook Beach.
He said about 30 people were swimming at the rock pool at the time.
A report will be prepared for the coroner.
Mr Walsh reminded swimmers to swim between the flags at Mollymook and Narrawallee beaches.
He said North Mollymook and South Narrawallee beaches would be patrolled by lifeguards and surf life saving volunteers until Wednesday January 27.
Patrols will continue at South Mollymook until the end of February.
He said apart from Wednesday’s incident, there had been no other serious issues at local beaches in recent days.