Crocodile Hunter Steve Irwin has died in a freak marine accident while shooting a documentary on the Great Barrier Reef.
The 44-year-old is believed to have been killed by a stingray barb that went through his chest while he was diving.
He was filming an underwater documentary off Port Douglas when the accident occurred.
Mr Irwin's body is being flown to a morgue in Cairns.
It's believed his American-born wife Terri is trekking on Cradle Mountain in Tasmania and authorities are trying to reach her with news of her husband's death.
Melbourne-born Mr Irwin - known worldwide as the Crocodile Hunter - is famous for his enthusiasm for wildlife and his catchcry "Crikey!".
The father of two's Crocodile Hunter program was first broadcast in 1992 and has been shown around the world on cable network Discovery.
Thanks to his TV programs, Irwin is perhaps the best-known Australian in the United States.
He has also starred in movies and developed the Australia Zoo wildlife park, north of Brisbane, which was started by his parents Bob and Lyn Irwin.
The Queensland Ambulance Service (QAS) said a call was received about 11am (AEST) on Monday and an emergency services helicopter was flown to a boat on Batt Reef, off Port Douglas, with a doctor and emergency services paramedic on board.
Mr Irwin had a puncture wound to the left side of his chest and he was pronounced dead at the scene.
If you haven't heard already, Steve Irwin died today on the 4th of September on the Barrier Reef near Cairns. As a sign of respect for the great australian cultural icon, please place a turtle ( tu ) at the start of your MSN name, and forward this message to others on your list, as he worked around sea animals most of the time and he was working in the sea when he died so a turtle is a good sign.