SANTA ANA, Calif. - Climbing Mount Everest takes weeks of acclimatizing, getting used to the altitude and little oxygen. The same is true in freediving, except you're going in the opposite direction with no oxygen at all.

For three weeks, George "Doc" Lopez of Laguna Beach, Calif., has been holding his breath and diving to new depths daily off the Cayman Islands. He is preparing for the Cayman 2006 Sink Faze on-April 7.

Lopez, 58, will be attempting to break the U.S. record of 165 feet in free immersion, and many among the 1,355 employees of his company, ICU Medical in San Clemente, will be following his progress via the Internet.

Performance Freediving, based in Vancouver, B.C., offers daily updates and videos on its Web site. Its team of three divers will be pursuing world and national records. Lopez is the lone American on the team.

Because Lopez is key to his company, the board of directors wasn't too keen about his diving at first but is OK with it now, he said.

"Other people think it's kind of crazy to hold your breath and go down that deep, and other people are amazed by it," Lopez added.

Amazing, too, is he is 30 years older than the next oldest competitor.

"Doc has amazing adaptation abilities at his age and for his physiology," said Kirk Krack, coach of the Performance Freediving team.

"His body type is designed more for boxing or jujitsu than a lean freediver adapting to depths of 165 feet and for times exceeding two minutes during a breath-hold dive. His mental focus and his drive to excellence during a dive are his greatest attributes."

Lopez, who grew up in Torrance, became adept in the water when he began spearfishing at age 9.

"That's where I got the ability to hold my breath," he said.

Lopez once speared a 330-pound marlin and aims to become the first to spear a 1,000-pound marlin.

To improve his spearfishing, Lopez took a freediving course with Performance Freediving in 2003.

When Lopez completed a free dive to 120 feet, double the depth of other students, Performance Freediving recruited him as a competitor.

Lopez then set out to establish the first American records in free immersion and variable ballast.

In April 2004, he set the standard in free immersion (diving without fins and under your own power) at 113 feet. It was broken last year at 165 feet.

In April 2005, he went 202 feet in variable ballast (riding a sled down and kicking up with fins).

Lopez left town adamant about pursuing both records but has since decided to concentrate on taking back the free immersion record.

"Even though the current USA record is 165 feet, I expect we'll see Doc getting close to the 200-foot depth mark," Krack said.

So, is this extreme sport dangerous? It can be if you are not prepared. Still, safety scuba divers are always nearby, minimizing the risk.

Yet, when Lopez described his record dive to 202 feet in variable ballast, one wonders.

He lies in the water and relaxes by meditating. He puts his fins in buckets, straddles the sled and packs his lungs with oxygen by gulping down air. He takes one last breath.

"Then I pull the release cord and down I go," Lopez said.

He pinches his nose and blows to equalize his ears as he descends feet first, carried by a sled on the fixed rope.

"If you miss an equalization, you'll blow an eardrum, and if you blow an eardrum, you'll start vomiting underwater," he said. "You get dizzy and vomit, and you're finished at that point because you'll never make it up."

Proper preparation - or acclimatizing - prevents such a scenario.

At 200 feet, the pressure sucks in his stomach, and his lungs shrink to the size of plums.

Upon reaching the target depth, he grabs the line and gives one pull upward and starts kicking.

"There's tremendous desire for oxygen, air hunger," he said. "You have to fight that, push it aside and relax."

The last 30 feet is where blackouts usually occur, but safety divers are there in case. For the record, Lopez surfaced like a seasoned veteran.

Like climbers of Everest, the question begs asking: Why?

"Because it's hard," Lopez said. "It's the challenge. It's the setting the record, having it broken and then taking it back."

• San Jose Mercury News