Police say a badly decomposed body found on a New South Wales south coast beach could be a man who tried to rescue a struggling swimmer last month.

Fifty-one-year-old Paul Quinlivan from Canberra drowned while trying to save a 22-year-old man who was swept off rocks at Pebbly Beach, near Bateman's Bay, on October 10.

The 22-year-old made it ashore safely but Mr Quinlivan was never found, despite a large-scale search involving various rescue agencies.

A tourist discovered a body around 8:00am AEDT today while walking along Pebbly Beach.

A post mortem is yet to be carried out.

Mr Quinlivan has been described as a man of great courage and compassion and a 'true hero'.

He worked with remote Aboriginal communities in Central Australia, and is credited for his work in delivering health care.

Mr Quinlivan will be recommended for a posthumous bravery award.

A report will be prepared for the coroner.