The venom researcher Struan Sutherland (who appeared in Last Chance To See) recounted one similar attach from 60 years ago.
In January 1945, a 33-year-old army sergeant took a dip in Melbourne's St Kilda Baths along with other soldiers.Full story at the Age.com.
A powerful swimmer, the soldier died with a nasty slash to his left breast. According to a doctor's notes — recorded by the renowned venom researcher Struan Sutherland in his 2001 book Australian Animal Toxins: The Creatures, Their Toxins, and Care of the Poisoned Patient — the stingray attack was sudden.
The soldier had been seen "swimming strongly from the centre of the baths towards the landing steps", say the notes of a Dr Wright-Smith, who performed the autopsy. The victim then disappeared below the water, resurfaced, waved and sank again.
Our sympathies to Steve Irwin's wife and young children.