Visitors and locals alike marveled in their wake — 40 to 50 feet high at Oahu, according to the National Weather Service.

“It’s crazy,” Peter Panais of Canada told CNN affiliate KHON. “Honestly, these are probably the biggest waves I’ve ever seen in my entire life.”

The ocean swells have plenty of wow factor.

This drone-shot video of surfers in Hawaii will blow your mind

“I’ve got some mates back in Aussie that I’ve already sent videos to, who keep asking for more videos, more videos,” said Australian visitor Micka Murphy. “They want to see more.”

But even the locals were impressed by the powerful waves.

“It’s a spectacle. It’s incredible,” North Shore resident Daniela Power said. “It’s so big and massive and powerful and it’s really a special thing to watch for sure.”

The heavy surf peaked Wednesday night, but waves were still supposed to reach 30 to 40 feet on Thursday. A high surf advisory will be in place until Friday morning.

Hawaii hasn’t experienced waves this large since 2004, said Sam Houston, a forecaster with the weather service.

Surfing event canceled

The massive waves would appear to be a surfer’s paradise, but organizers of a big wave surf contest postponed this week’s event. Although they said the waves measured up, the wind conditions didn’t.

“We have taken all the time we can to assess the developments of the next big swell and it does not look favorable for us,” event organizer Glen Moncata said at the beginning of the week. “The size is there, but the quality is not, due to strong, adverse winds.”

Organizers of the big wave event said they will keep waiting until the end of February for “just one day of quality surf” when wave face heights reach around 40 feet.

The contest is held in honor of Eddie Aikau, a famous Oahu lifeguard who was regarded as one of the best big wave surfers of the 1960s and ’70s. Aikau disappeared in 1978 during a canoe expedition from Hawaii to Tahiti.

The event — the Quiksilver In Memory of Eddie Aikau big wave invitational — isn’t an annual occurrence. It has taken place eight times, starting in 1984. It was last held in December 2009 when Greg Long of California claimed victory.

The invitees to this year’s event include Long, Aiku’s younger brother Clyde, 11-time world champion Kelly Slater and Carlos Burle, who gained global renown for surfing an enormous wave in Portugal last year.

Why such huge waves?

A large storm with hurricane-force winds is spinning far north of the islands, but is sending a giant swell toward the warning areas, according to CNN meteorologist Brandon Miller.

Althought fun to watch, the big waves are prompting concern among beachfront home owners whose houses risk being flooded or are on cliffs vulnerable to erosion.

The American Red Cross says it has volunteers and supplies on standby for any homes that are affected, CNN affiliate KHNL/KGMB reported.