O'ahu's Ocean Safety lifeguards were kept busy on all shores yesterday, making rescues, warning people to avoid risky situations and dealing with Portuguese man-of-war stings.

According to Ocean Safety spokesman Brian Cheplic, North Shore lifeguards rescued 18 people and conducted a total of 1,725 preventative actions (hazard warnings) yesterday. The bulk of those rescues and warnings took place at Waimea Bay, where the surf was high, he said.

Meanwhile, on the south and leeward shores, there were a number of Portuguese man-of-war sightings, with eight confirmed stings at Ala Moana Beach, Cheplic said.

"With extended periods of south winds, it's not unusual to have Portuguese man-of-war showing up on the south shores," he said.

If all that isn't enough, Cheplic issued a reminder that today begins the monthly box jellyfish influx.

He asked swimmers to check with lifeguards before entering the water in case jellyfish have been sighted in the area.

Reach Will Hoover at whoover@honoluluadvertiser.com.