Members of the public called emergency services to Woongarra Scenic Drive at about 5.50pm yesterday.
They were told a swimmer, described as a Caucasian male with a bald head, had not resurfaced.
A search operation was launched but suspended at about 10pm.
It will resume at 6am (AEST) today, with support from specialist officers, lifesavers, the SES, Volunteer Marine Rescue, and LifeFlight.
Anybody with information that could help is urged to contact police. No missing persons have been reported.