Kalani Lattanzi bobbed in the lineup of one of the world’s most fearsome surf breaks with little more than swim fins.

A 28-year-old bodysurfer from Brazil, Lattanzi was treading water at Peahi, the renowned surf spot on the north shore of Maui that is known to most as Jaws, waiting for a massive wall of water. When a 20-foot wave approached, he kicked his fins and swam ferociously to catch it.

Without the support of a surfboard, Lattanzi tautened his body and extended his arms onto a handplane, a board about the size of a serving platter. Gliding through the tunnel created by the curling wave, he became one of the few bodysurfers to ride through the barrel of a big wave at Jaws.

“Best barrel of my life,” Lattanzi said. In an Instagram story, Kelly Slater, an 11-time World Surf League champion, anointed Lattanzi’s performance “one of the all-time great rides in the surf world.”

It was the latest jaw-dropping feat Lattanzi added to his resume. Since he burst onto the scene in 2015 by bodysurfing 30- to 40-foot waves off the coast of Nazare, Portugal, the Mount Everest of wave riding, Lattanzi has tackled some of the biggest surf on the planet.

In the process, he has pushed the boundaries of big-wave bodysurfing, a niche discipline in which surfers catch and ride monster waves with their bodies, a pair of swim fins and at times a handplane, a device that can make waves easier to ride (and one that some purists view as a crutch).

“It’s one of the most extreme things I’ve ever seen,” said Nic von Rupp, a professional big-wave surfer. “It’s so extreme it’s like hanging from the wing of an airplane while everyone is sitting inside.”

Bodysurfing is one of the most ancient forms of wave riding, one that has enjoyed a surge in competitions and participants in recent years. While there is no organized circuit of competition, in January a national governing body was founded in the United States with the goal of getting the sport into the 2032 Summer Olympics in Brisbane, Australia.

The sport’s devotees call it one of the purest forms of any sort of wave riding. “It’s like every cell in your body is humming with the energy of the ocean,” said Ryan Masters, a big-wave bodysurfer from Santa Cruz, Calif. “I believe it’s the closest you can get to really physically experiencing the universe’s tangible energy — call that God or whatever.”

Catching a big wave requires bodysurfers to position themselves in the lineup as a surfer would, treading water until the right wave arrives. That can take a while: Lattanzi once treaded water for four hours to catch three waves off Nazare.

Once the right wave approaches, bodysurfers must generate as much speed as possible by swimming and kicking their fins, then they use their arms, torso and legs to control direction and speed while inside the wave. Some bodysurfers like Mike Stewart, one of the few people to bodysurf a wave off the coast of Teahupoo, Tahiti — considered to be one of the world’s most lethal — looks to seals, dolphins and otters for how to best maneuver in the water.

Because bodysurfers ride headfirst into massive waves, it might seem a more dangerous style than boardsurfing, especially so for novice riders, who tend to catch waves in shallow water and might not know how to avoid head-planting when the wave breaks. Whereas boardsurfers are more likely to receive lacerations from being hit by their boards, bodysurfers are more likely to come into contact with the seafloor, which can cause devastating cervical spine injuries, said Pascal Juang, an emergency room physician at Hoag Hospital in Newport Beach, Calif.

But some say that experienced big-wave bodysurfers might actually be safer without a board. “It looks so much scarier, not having a board, but if you’re a strong swimmer and have fins on and know the lineup and have a high degree of big-wave knowledge, you’re better off than being on a board with no fins,” said Matt Warshaw, author of “The Encyclopedia of Surfing.”

BOBBING and diving through huge surf like a seal, Lattanzi is remarkably at ease, which he credits to a lifetime spent in the water. He got his start bodysurfing at age 12 in Itacoatiara, Brazil, and had dreams of charging monster waves.

“When I started bodysurfing, I wondered if it was possible for someone to bodysurf a big wave,” he said. “Then I started to grow up and I realized, ‘OK, I am the one who is going to do this.’”

By 2011, at 17 years old, he was bodysurfing in Arica, Chile, and Puerto Escondido, Mexico, a big-wave capital of the world. In 2015 he headed to Nazare, where he spent the next six years catching some of the biggest waves bodysurfed, some as high as 40 feet, a death-defying feat akin to diving off a four-story building.

“He’s in a league of his own,” said Mark Drewelow, a competitive bodysurfer from Encinitas, Calif.

Lattanzi prepares like a professional athlete in order to meet the demands of his niche. He eats clean and cross-trains, lifting weights and doing yoga in order to sustain the many hours of swimming, negotiate huge waves and withstand their impact. He now has his sights set on Mavericks, a notoriously dangerous wave in Northern California that can reach heights of more than 60 feet, which he hopes to tackle this year.

“It takes a real tranquil mind. It takes incredible strength. Incredible lungs. Aqua Gorilla is what we all call him because he’s so strong in the water,” Masters said. “He’s the ultimate waterman.”

When Masters tried to conquer Mavericks in 2016, he bruised a lung, fractured his neck, broke his collarbone and seven ribs, and was airlifted to Stanford Hospital.

“Mavericks is just a different animal that’s unlike any wave on the planet,” Masters said. “It’s incredibly savage.”

Given the risks, some wonder why Lattanzi is willing to paddle out to the world’s most dangerous surf breaks. Even Mark Cunningham, widely considered the best bodysurfer of all time, has found himself wondering: “He’s swimming out in water I wouldn’t even consider. What’s driving him?”

For Lattanzi, it is simple.

“Because I love it,” he said. “I love the adrenaline. I love this feeling of being surrounded by water and finding the biggest barrels and pushing my limits. I’m chasing adrenaline for sure.”