Despite medical treatment the sailor could not be revived, Defence said in a statement.
“It is with deep regret the Australian Defence Force can confirm the death of a Royal Australian Navy sailor in the Middle East,” the statement said.
“The sailor was deployed on Operation Manitou in HMAS Darwin.
“The ship was in Muscat, Oman on a scheduled port visit and the sailor was on shore leave in the city when he was found unconscious.”
The sailor was a 22-year-old man.
The sailor was part of Operation Manitou and serving on HMAS Darwin, based in Woolloomooloo, Sydney.
Defence said it is assisting local authorities with an investigation but it is not appropriate to provide further details at this time.
Defence extended deep condolences to the sailor’s family and friends.