At midday, waves were between 12 feet and 18 feet at Waimea Bay, lifeguards said.

Dozens of surfers were in the water, and spectators lined the beach. But the beach was closed, with "no swimming" signs posted due to the high surf.

The situation was similar at Pipeline, where bodyboarders were out practicing for a competition set to begin Monday. But they said the waves were too big and not breaking well.

On the Wai'anae Coast, waves were big enough to wash a disabled 54-foot yacht onto shore close to the Army Recreation Center near Pokai Bay.

The National Weather Service said waves on O'ahu's west-facing shores were 12 feet to 20 feet. Warning signs were posted at some beaches.