Surfers, swimmers and divers have been warned to stay out of the ocean at Bulli near Wollongong on NSW's south coast, where a whale carcass has prompted a shark feeding frenzy.
Three large sharks got to work on the carcass as it floated past Bulli ocean pool, about 150m out at sea, about 4.30pm Thursday.
Numerous passers-by mistook the whale for an overturned boat and raised the alarm with authorities.
Surf Life Saving Illawarra duty officer Anthony Turner confirmed the object was a whale carcass.
The thrashing from the feeding was visible to onlookers watching from shore - a sign of the sharks' size.
"It was actually quite spectacular to watch," Mr Turner said. "Nature at its best."
"But people need to exercise caution and stay out of the water while they're feeding. Even after the whale is gone, there will still be remnants in the water."
At last light the whale was pressed up against the reef break known as Peggy's, at the northern end of Bulli Beach.
Unconfirmed reports are that the feeding sharks are tiger sharks.
Authorities will monitor the whale's progress on Friday morning.
"It's likely it will wash up sometime tomorrow morning, just depending on the tide and winds," Mr Turner said.