Tributes have poured in for an Australian Navy sailor who died on a maritime patrol operation.
Defence confirmed the death of the sailor aboard an Australian Defence Vessel Cape Inscription on Tuesday afternoon.
The sailor was deployed under Operation Resolute which conducts patrols to combat asylum seeker boat arrivals, illegal fishing and piracy in Australian waters and around offshore territories.
Chief of the Defence Force Mark Binskin expressed his deepest sympathy to the family, friends and shipmates of the deceased.
"Defence is liaising with local authorities and the cause of death is not yet known," a Defence spokesman said.
"As such, it is not appropriate to provide further details at this time."
A few messages on social media paid tribute to an "outstanding bloke and outstanding servant to the RAN over the 30+ years."
Another wrote: "Sad loss to the NT Navel (sic) Community. A successful sailor and much loved. RIP. Condolences to his family".
Defence Minister Marise Payne also shared her sympathies on behalf of the federal government to the sailor's family, colleagues and friends.
"I express my gratitude for the deceased member's service to our nation," she said in a statement.
Labor's federal defence spokesman Richard Marles labelled it a sad day.
"Our Defence Force members do difficult and extraordinary work to keep our community safe, and we, like the Australian community, value that work deeply," he said.