A south swell this morning started delivering the goods ­ waves up to 5 feet measured in the old style, from the back, or 6-10 feet by the new standard, measured from the front ­ at Sandy Beach, Diamond Head, Ala Moana and Waikiki.

And forecasters for the National Weather Service believe the swell may begin to decline overnight.

"It looks like the surf will be peaking today, and tonight it'll probably start dropping off," said lead forecaster Pete Donaldson.

Donaldson said the swell originated from a storm that developed east of New Zealand more than a week ago and was tracked as the waves crossed buoys at the equator and more than 200 miles south and southwest of Honolulu.

The closer buoys are still measuring a continuation of the swell, which means that the advisory will remain in effect at least until 4 p.m. today, he added.

Beyond that, nobody can be sure, and experienced surfers know not to wait.

"We expect it to get bigger," said lifeguard Capt. Kendell Rust. "This afternoon it should start pumping, as we surfers say.

"Today is the day, really, for the guys who like the big stuff."