Waves on Oahu's North Shore appear to have peaked this morning at somewhat below the 25- to 30-foot heights that had been forecast, said Bryan Cheplic, spokesman for the city Emergency Services Department.

Even so, anyone venturing to the water should exercise extreme caution and check with area lifeguards before doing so.

Although the waves are not quite as big as expected, they still pose a formidable threat to all but the most experienced surfers and swimmers, Cheplic said.

"We're asking anyone who goes to the beach to heed the warning signs," Cheplic said. "This is a very long-period swell, meaning the ocean may appear flat between sets, but we expect the surf to be very strong throughout the day," Cheplic said.