Malua Bay Beach in New South Wales shut promptly on Monday after a few sharks swam close to the shore.
Officials told everyone to get out of the water immediately when massive sharks appeared in shallow waves.
A 3.45-metre tiger shark, large shark, only fitted with a identification device, was spotted nearby.
Local shark detections have been rising.
The beach stayed shut while coast guard checked the area.
Fortunately no one near the sharks got hurt.