Flocks of visitors crowded behind yellow caution tape stripped across North Shore beaches, which Thursday saw an influx of people trying to catch a glimpse of the 30- to 40-foot waves pummeling the shoreline.

A high-surf warning went into effect Thursday for the north and west shores of most of the Hawaiian Islands through 6 p.m. today, resulting in numerous road closures and restricting access to Kaena Point State Park.

Lifeguard Lt. Kerry Atwood, who patrols the North Shore for the Ocean Safety and Lifeguard Serv­ices Division of Honolulu Emergency Services, said he thinks there were “way more people” in the area than usual, judging by the amount of both car and foot traffic.

Atwood said unfavorable winds created less-than-ideal surfing conditions. Ocean Safety prioritized shoreline management with ensuring that visitors didn’t get too close to the surf by bypassing caution tape.

“It’s been a very busy day for us here at Ocean Safety,” he said. “Lots of shoreline management but not a whole lot of ocean rescues. … There are some guys surfing out at Waimea, but at this point maybe 10 to 15 guys, when normally it would be three times that.”

Atwood said that early Thursday morning, Ocean Safety saw moderate surf in the 6- to 10-foot range, but the surf increased gradually as the day progressed. By late afternoon, surf was hitting 35- to 45-foot face values.

The Mokuleia Section gate of Kaena Point State Park was closed to vehicles due to road conditions and large surf along coastal roads, and the Keawaula gate was closed due to dangerous shore break, according to the state Department of Land and Natural Resources Division of State Parks.

The National Weather Serv­ice said in a Thursday afternoon advisory that north-facing shores would see surf of 30 to 40 feet, and west-facing shores would see surf of 20 to 25 feet following an “extra large northwest swell” that would peak that afternoon. The organization also said coastal areas would likely be affected with ocean water run-up, especially during the evening high-tide periods.

NWS warned that impacts of the swell would be “very high” and wrote that “ocean water surging and sweeping across beaches, coastal benches and lava flows create the potential for impacts to coastal properties and infrastructure, including roadways.”

“Ocean Safety is coordinating with the Department of Emergency Management. We’ve been giving them shoreline updates throughout the day, and they’ve been assisting us on standby, ready to close beach parks or roads should we start seeing water inundating these areas,” Atwood said.

People were advised to stay away from the shorelines of the north and west shores. The City and County of Honolulu’s alert system also warned that people should avoid walking on beaches or rock ledges that are wet, as that indicates that waves are washing over those areas.

“In some of our other areas, like our Sharks Cove area and our Three Tables area that’s very popular for people viewing the surf, we do have caution tape up and signs, and we strongly recommend you stay behind the caution tape, and absolutely do not venture out onto wet rocks or wet sand,” Atwood said.

Atwood also advised that visitors who come out to view the surf do so at beach parks with permanent lifeguard towers, as mobile responders take longer to respond to incidents at more secluded areas.

Atwood said Ocean Safety expected the surf to peak Thursday night but that the waves will still be big today.

“This isn’t just another high-surf advisory,” he said. “This is some really big surf and life-threatening conditions.”