The body of a 19-year-old Canadian woman was found on a beach surrounded by dingoes; officials said it was too early to determine the cause of death.

A 12-year-old is in critical condition after a shark attack in Sydney Harbour, with his friends being praised for saving his life.

"We believe the combination of the brackish water, the fresh water, the actions of the splashing may have made that perfect storm environment for that shark attack yesterday," McNulty said.