The Crocodile hunter Steve Irwin has died.

Irwin, 44, was killed almost instantly when the stingray stabbed him in the heart with its poisonous 20cm barb as he snorkelled off Port Douglas, in north Queensland, yesterday morning.

His American-born wife, Terri, was trekking in Tasmania's Cradle Mountain and Lake St Clair National Park when the news broke of her husband's death and was last night being raced back to Queensland with her two children Bindi, 8, and Bob, 2.

"The footage shows him swimming in the water, the ray stopped and turned and that was it," said boatowner Peter West, who viewed the footage afterwards.

"There was no blood in the water, it was not that obvious ... something happened with this animal that made it rear and he was at the wrong position at the wrong time and if it hit him anywhere else we would not be talking about a fatality."

This is just a damn shame. Irwin was one of the truly unique individuals in the world.