Nine-year-old Minnesotan Calvin Kotrba described the wave action at Waimea Bay when it got totally tubular yesterday.

"Like a circle, almost like a tube," he said. "It looks like you could almost go through the pipe until it crashes."

The late-winter megawaves and big-wave riders delighted, mesmerized and inspired awe in kids and adults — visitors and locals alike.

Surf heights averaged 20 to 30 feet on Oahu’s North Shore yesterday and 20 feet on the West Shore.

The National Weather Service forecasts the swell will subside through Friday. The surf will die down today to 12- to 16-foot faces for north shores, 8 to 12 feet for west-facing shores and 4 to 7 feet on east-facing shores.

The Weather Service also issued a wind advisory for 6 a.m. today until 6 a.m. tomorrow for strong and gusty east winds for all areas except Hawaii County summits.

Lifeguards made 24 rescues and assists and issued 2,375 warnings yesterday, Ocean Safety Division officials said.

Lifeguards rescued a personal watercraft rider at about 3:30 p.m. yesterday in Haleiwa at a surf spot called Avalanche after he got separated from the watercraft while in the surf lineup.

Back on land, Paul Hillman of Ontario, Canada, said, "We were just driving by, and we said, ‘Holy smokes, we gotta stop.’"

His son, Justin, 11, watched surfers from the beach at Waimea, saying, "Aww, wipeout."

"I like to see guys wipe out," he said.

Fellow Ontarian and firefighter Mark McLean had a similar sentiment: "I could watch this all day. I’d like to catch a rescue — not a tragedy, a rescue," he said, adding that he performs water rescues but nothing like what the Hawaii lifeguards perform.

After one really good ride, Brazilian surfer Caio Marcoantonio, 37, wiped out. "I fell down in a really hollow wave," he said, and had to rest for a half-hour before continuing on.

But he said conditions were perfect. "People are all friendly out there," said Marcoantonio, who arrived from Ubatuba, Brazil, early to surf before attending a conference later this month.

Adam Bechok, 35, of Kaaawa, a self-employed carpenter, took a planned vacation day, surfing from 7:30 a.m. to noon.

"I got four or five waves, and they were all fairly fun," he said. "As far as a late-season swell, we’re fairly fortunate to have this-size big surf."

Without surf contests it was mostly "the local crew" and fewer people, about 25 or so at Waimea, he said. "If this was during the Eddie (Aikau tournament), there would be so many people," he said.

As for surfing the big waves, Bechok said, "When you actually realize you’re into the wave and make it to the bottom, it’s a huge relief."

"There’s not a lot of mental meandering at that time," he said. "There’s a few who are desensitized to that. You can stay calm. With more experience it becomes more playful as far as the enjoyment. You’re not doing it to torture yourself."

He said last week’s tsunami experience has taught about the strength of the ocean, and "you can spend a lifetime trying to figure out" how to predict what happens.

Honza Vorel, 34, of Jackson, Wyo., stood watching the surf, and said, "I’ve never had a chance to see Eddie Aikau’s competitions, but it’s still highly entertaining. Eddie Aikau is my hero — the most famous lifeguard out of Waimea Bay."

Vorel, who has surfed the Snake River in Wyoming, spent his vacation surfing the North Shore, but yesterday was too big.

In addition to waves, Amanda Poitras, 34, and her teenage cousins from Seattle got an added treat. "We saw whales right out here," she said.

"I’ve taken four or five trips, and I’ve lived here a year and a half and never saw whales before."