There's an article on Time.com here:
Link
$this->bbcode_second_pass_quote('', 'T')his morning, at 11am Australian time, things finally came unglued for the 44-year-old as he was shooting a documentary segment on stingrays. Snorkeling on Batt Reef , a stretch of the Great Barrier Reef about 15km from Port Douglas in North Queensland, Irwin happened to swim over a large ray which, startled, whipped its barbed tail upwards into his chest. He died instantly. Veteran marine wildlife documentary maker Ben Cropp, who has spent hundreds of hours filming on Batt Reef, says Irwin had come too close to a bull ray. Citing a colleague who saw footage of the attack, Cropp says Irwin had accidently boxed the animal in, causing it to attack. "It stopped and twisted and threw up its tail with the spike, and it caught him in the chest," says Cropp. "It's a defensive thing. It's like being stabbed with a dirty dagger." Says Cropp: "It's a one-in-a-million thing. I have swum with many rays, and I have only had one do that to me."
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Some in the animal conservation world felt it was perhaps inevitable that this larger-than-life figure would someday take one too many risks. "He had a long history of doing this kind of thing with dangerous animals; some people do these things and get away with it, and other times your number comes up," says Professor Grahame Webb, a crocodile expert who operates a crocodile park in Darwin. "He had huge experience with crocodiles and snakes and reptiles, but stingrays are quite different."
So rays kill 6 times as many Australians every year as crocodiles, and he was trying to get all cheeky with them for a TV segment. Not bright, IMHO.