A shark sighting at Manly forced the immediate closure of the beach just hours after flags were raised for the day.

Swimmers quickly fled the water after a shark alarm was activated following the sighting near Manly Beach, prompting authorities to shut down the stretch of coastline from Manly Beach to Queenscliff.

Local residents acknowledged the risks, noting that sharks are a natural presence in the ocean and that swimming always carries an element of danger. They also emphasised that humans share the water with marine life and must remain aware of the risks involved.

The closure comes as authorities remain on high alert after a series of shark attacks across the state earlier this week, with four separate incidents reported within a 48-hour period.

Officials are currently assessing the area, and the beach will reopen once it is declared safe.

Meanwhile, Surf Life Saving has intensified safety measures for the long weekend, increasing drone surveillance and deploying additional rescue crews to protect beachgoers.