"We had a phone call from one individual [a 42-year-old man], who we located on the far side of Awonga Dam and he assisted us to find his vessel, which was going in concentric circles – so it was going round and round with nobody on board in the middle of the dam," Sergeant Barnett said.

"He swam a considerable distance, he told us for anywhere between 30-40 minutes to get to shore and at that time he was physically exhausted and suffering from mild hypothermia.

"You could see the vessel from where we located him [the survivor], still going round in circles, and it was about 300-400 metres.

"[The deceased man] was within our search area, he was within 200-300 metres of where the vessel was going round and round."

The 42-year-old man was taken to Gladstone Hospital with non-life-threatening injuries after the body of his 68-year-old male companion had been found.

Sergeant Barnett said the incident highlighted the importance of lifejackets and a safety lanyard, with the deceased man being found in the water without a lifejacket.

Maritime Safety Queensland, Gladstone water police and scenes of crime investigators were preparing a report for the coroner.