A tourist walking along the beach, near Batemans Bay, at 7.30am today discovered the man's body, which had washed up during a high tide.

Police are investigating whether the body is that of Northern Territory man Paul Quinlivan, who has not been seen since October 11 when he dived into the ocean off Pebbly Beach to rescue a 22-year-old Ashfield man.

Mr Quinlivan had been sketching a seascape with his daughter about 11am when a freak wave hit the northern rock shelf on the beach.

The 22-year-old man had been walking on the rocks with a group of young people when the wave hit and sent him into the sea.

Mr Quinlivan dived in after the younger man, who became caught in a rip and was carried 100m out to sea.

The younger man was later discovered alive and well on a nearby beach.

A large-scale search failed to find Mr Quinlivan, who will be recommended for a posthumous bravery award for his actions.

Mr Quinlivan had spent the past 25 years working in Aboriginal communities in the Northern Territory and Western Australia.

A police spokesperson said a post mortem would be conducted to determine the cause of the man's death, and a report would be prepared for the coroner.