The Department of Defence has identified the Royal Australian Navy member who died while deployed on a border patrol operation as Lieutenant Commander Steven Noakes.
A statement released by Defence on behalf of his family described Lieutenant Commander Noakes as "a much loved husband, father, brother, uncle, son and proud Navy member".
"He devoted 36 years of his life to serving his country and for that we couldn't be more proud of him," the statement said.
"When not home with his family, he was most happiest when at sea with his crew.
"We wish to extend our thanks to his shipmates and colleagues who provided such a rewarding and joyous career to Steven over the years."
Lieutenant Commander Noakes was deployed on patrol boat Cape Inscription as part of Operation Resolute.
A Defence spokeswoman said the cause of death was not yet known.
"Defence is liaising with local authorities and the cause of death is not yet known," the spokeswoman said.
"As such, it is not appropriate to provide further details at this time."
Operation Resolute was launched to stop unauthorised maritime arrivals, piracy, illegal fishing and prohibited imports.
The operation covers close to 10 per cent of the world's surface from the Christmas Island to Norfolk Island.
