Police in New South Wales were alerted that a man staying on the boat with friends, had fallen from the top deck into the water.
It’s believed that the man named as Niall Quinn may have hit his head in the fall.
Police, divers, local marine rescue and local residents assisted in a search.
His body was located around two hours later by Victoria Police divers.
The Irish Department of Foreign Affairs is providing consular assistance to Mr Quinn’s family.