Ocean Safety officials say shark warning signs were posted at Maili Wednesday after a 10-foot-long shark was confirmed swimming near the shoreline.
The shark was seen in the area 30 minutes later.
Lifeguards were also busy on south shores with 4-to-6-foot surf. There were 154 preventative actions at Ala Moana on Wednesday with three rescues.
There were 100 preventative actions at Sandy Beach.
Call 911 if you suspect someone is in trouble in the ocean or if you need to report a broken board that was not recovered.