The way Ben Mercier views it, he isn't swimming "crazy and fast" anymore. He's just bodysurfing.

But the former collegiate All-American swimmer has turned surfing's purest discipline into a heart-pounding cardiovascular workout that can last up to three hours.

"When I bodysurf, I really get into it," said Mercier, who swam the 200-meter butterfly at the University of Hawai'i from 1992 to 1997. "I will stay out there until my calves cramp and I can't swim."

Bodysurfing is one of those hurry-up-and-wait activities. Treading water and waiting for the right wave is part of the sport.

Not for Mercier, though.

"I usually catch 100 waves a session," he said. "I catch a wave and sprint back out. Holding my breath, I'll do underwater takeoffs like a dolphin and time it just right so I can come out on the lip."

It leaves his heart "going 100 mph."

Mercier discovered bodysurfing when he left landlocked Fresno, Calif., for the UH swim team. A year into his collegiate career, Mercier started bodysurfing between classes.

Bodysurfing was a natural evolution for Mercier, who started swimming competitively at age 4. It was like having an extra workout and helped propel him to the finals in his event at the NCAA championships in 1994. He was ranked 21st in the world that year.

Now a 32-year-old captain in the Marines with two tours in Iraq, Mercier considers bodysurfing his primary exercise. Each weekend, the Ka'a'awa resident will drive to wherever waves are breaking — Pyramid Rock, Sandy's, Point Panic, Waimea Bay.

Catching a wave taps into the swimming skill that Mercier used successfully in college — the dolphin kick. With legs and feet held together and moving in unison, it becomes a full-body motion that powers butterfly specialists through the water.

"You push a wave motion down your body," he said. "You catch the wave as it is still building."

Mercier will drive himself through the water — underwater — with his arms pointed ahead of him and keep going for 5 to 7 seconds before popping out on the face of the wave.

No pool workout could ever compare to that, he said.

Reach Mike Gordon at mgordon@honoluluadvertiser.com.