Malua Bay Beach in New South Wales shut abruptly on Monday after a few sharks swam close to the bank.
Officials told everyone to get out of the water without delay when big sharks appeared in shallow waves.
A 3.45-metre tiger shark, large shark, only fitted with a identification device, was spotted nearby.
Local encounters have been going up.
The beach stayed shut while rangers checked the zone.
No one near the predators got hurt.