I understand he was hovering right above this huge ray and his cameraman positioned himself in from of the ray (blocking the rays egress in the process) for a better shot and that spooked the ray and it defended itself. Steve pushed the outside of the envelope once again but this time it pushed back.
I respect him but having taken risks in things myself in my youth, I see it as not unexpected and he finally lost one.
The Australian authorities disagree.
'Irwin didn't intimidate stingray'
Police have viewed video footage of Crocodile Hunter Steve Irwin's final moments and ruled out that he was intimidating or threatening the stingray that killed him.