A body, believed to be that of missing Irishman Shane OHalloran, was pulled from the Brisbane river, which flows through Brisbane in southeast Queensland, on Tuesday night.
A spokesman for the Department of Foreign Affairs said the body is expected to be formally identified as that of Mr O’Halloran.
It is understood that Mr O’Halloran drowned after apparently diving overboard from a cruise ship to save a female friend.
The pair were among about 120 people celebrating the 24th birthday of a friend on board the Lady Brisbane when the 26-year-old Irish woman fell overboard. The woman was rescued.