A man from Queensland was killed while surfing on Salt Beach near Kingscliff on the far north coast of New South Wales, according to Surf Life Saving New South Wales.
The beaches between Kingscliff and Cabarita will be closed for 24 hours.
The area is now monitored by members of the first police, police and biologists.
Surf Life Saving has deployed several jet skis, drones and helicopters to find the shark. Authorities noticed it from the air and took photos.
Shark biologists evaluated these photos and human bite marks and determined that it was a large great white shark that was about three meters (9.8 feet), according to Surf Life Saving.