The largest south swell so far this season, coupled with a rip current in Waikiki, kept lifeguards on their toes yesterday along Oahu's south shore.

With surf heights forecast to be in the 6- to 9-foot range today, lifeguards are bracing for another busy day.

Yesterday, lifeguards performed 35 rescues and took 525 preventive actions in Waikiki, said Bryan Cheplic, spokesman for the city Emergency Services Department. In the Ala Moana Beach Park area, no one had to be rescued, although lifeguards made 65 preventive actions, he said.

No one was seriously injured in any of the incidents, Cheplic said.

He said much of the activity occurred in front of the Sheraton Waikiki hotel, where he said the large swell from the southeast caused a strong rip current.

"That's why we had such a high rescue count in Waikiki today, primarily swimmers fronting the Sheraton," Cheplic said. "It's just an odd angle of the swell."

The National Weather Service yesterday extended a high surf advisory for south-facing shores through 6 a.m. tomorrow. Forecaster Vic Dejesus said surf today could be higher than yesterday and said the advisory could be extended through tomorrow.

Dejesus said the surf along the south shores should begin to drop beginning Thursday. But while the waves on one shore are dying down, the surf along the North Shore is forecast to rise later this week.

"There's been a little bit of out-of-season activity in the North Pacific that's sending a modest little pulse," he said. "There might be a little bump up midweek and something more of interest as far as surfing goes maybe Friday. It'll probably be the biggest surf up there. It might be head high or a little bit over head."