Three fishermen were not wearing life jackets when their boat capsized near Kurnell, just outside Sydney's Botany Heads, killing one and forcing the others to swim to safety, authorities say.
A 73-year-old man was unable to be revived after the trio were tossed from their overturned boat near the Cape Solander lighthouse.
He was recovered from the water by officers from the Botany Bay Marine Area Command who performed CPR to no success.
The man's son and another man managed to swim to nearby rocks. One of the men was able to walk to safety while the other needed to be winched by helicopter from the base of a cliff.
Both men were treated at the scene by paramedics before being taken to hospital in a stable condition.
One of the men reportedly sustained a severed thumb.
Police said the small fishing boat likely got too close to the rocks causing it to overturn.
The incident prompted authorities to reiterate their plea for people to wear life jackets.
"Whether they've put their lives at risk will be part of the investigation, at this point we will encourage that all people do wear life jackets, especially at sea, especially operating close to rocks and fishing," Inspector Darren Wood said.
"It is your best chance of survival should you be thrown into the water, to be wearing that jacket."
Inspector Wood also urged boaties to understand the conditions and have local knowledge of where they were fishing.
A report will be prepared for the information of the coroner.
