The man was bitten while swimming with others off North West Island, according to police in Queensland, Australia.
Tragedy struck as the group headed back to their charter vessel, police said. Members of the RACQ Capricorn Helicopter Rescue Service attended the scene.
Queensland Police added in a statement: “A doctor and paramedics responded to the scene and treated the man on board the vessel before he was transported to Gladstone Hospital.
“The man sustained life-threatening injuries to his leg, hand and elbow. He succumbed to those injuries just after 10pm.”
A police report is now being prepared for the coroner.
The victim worked as a ranger for the Queensland Parks and Wildlife Service (QPWS).
According to a statement from QPWS, the man was on North West Island “with colleagues, to complete maintenance works as part of the QPWS essential works program.”
The online statement continued: “Our deepest thoughts and condolences go out to the family, loved ones and friends of our dear colleague. Support has been organised for all those impacted by this tragedy.”
Annastacia Palaszczuk, the state premier, expressed her sympathy on Twitter.
North West Island, a popular spot for walking, diving, snorkeling and fishing, is located about 46 miles off the coast of the city of Gladstone, Queensland.
A nine-year-old girl was bitten in the leg in January. Days before, a 30-year-old man was bitten in the leg and sustained minor injuries. Both survived.
In October, a British tourist lost a foot after being bitten by a shark near Airlie Beach in Queensland. He and another Briton were attacked while on a snorkeling trip to the nearby Whitsunday Islands.