Chris Welsh is the kind of man little boys dream of becoming, a rare, boundary-pushing breed whose life is full of exploration, derring-do and far-off places. He's a nerves-of-steel guy who flies planes and helicopters, races boats, goes on off-road dirt bike journeys and swims with great white sharks.

Now Welsh is poised to embark on the adventure of a lifetime, a solo ride to the deepest reaches of the ocean, a project so startlingly daring that Welsh convinced Sir Richard Branson — the British billionaire whose resume also includes the title "adventurer" — to help foot the bill.

Like a modern-day Lewis and Clark, the pair hopes to blaze a trail that could open new vistas of understanding about the least-explored areas on earth.

It's no wonder that Welsh, who lives in Newport Beach, drew a huge crowd to hear him speak Wednesday at the Balboa Pavilion, part of a lecture series sponsored by the Newport Harbor Nautical Museum.

The audience was riveted as Welsh matter-of-factly explained his planned voyage to the bottom of the sea in a tiny, plane-like submarine made of carbon fiber and titanium that looks like something out of a James Cameron movie.

I met with Welsh the following day, and I was again struck by his no-fuss, easygoing manner, which seems at odds with the inherent drama of his project to plumb the ocean depths. Indeed, he discussed the upcoming voyage as calmly as if it was a weekend sail to Catalina.

"I'm very practical and pragmatic about things," he said.

Exploration is as natural to Welsh as breathing, but the self-described "control freak" prepares meticulously and calculates risks methodically, drawing confidence from knowing every inch of the craft he'll be piloting.

A big, shaggy-haired man with a graying beard, Welsh was raised in a family of sailors. He attended Mariners Elementary, Ensign Middle and Newport Harbor High schools, and UC Berkeley. A successful real estate investor, Welsh is also well known on the racing circuit, and in 2008 won the Sydney-to-Hobart Race in Australia with his 65-foot sailboat, Ragtime.

Welsh is also a bit of a science and tech geek: It's obvious that he's driven more by the chance to advance knowledge than a desire to set records or win accolades. There's not a whit of braggadocio about him — and it's precisely that lack of cockiness that makes me think this guy is going to do exactly what he sets out to do.

And what he's planning is enough to send a lesser man's blood pressure skyrocketing.

Welsh's latest quest started when he looked into buying a catamaran owned by the late aviator-adventurer Steve Fossett. At the time, he was asked if he might also be interested in Fossett's experimental one-man submarine. When Welsh saw the sub, it was love at first sight.

"It was a water-born flying machine, and I wanted to fly it," he said.

After buying the sub, Welsh set about trying to meet Branson, who had been a good friend of Fossett's. Branson signed on, and the venture, now dubbed Virgin Oceanic, is under the umbrella of Branson's Virgin Group of companies.

The sub is being completed by famed designer Graham Hawkes in Northern California. If all goes as planned, it will arrive in Newport in about a month, where it will be nestled on the giant catamaran, Cheyenne, in the middle of the harbor and taken on test dives in the waters off G Street.

When the testing is finished, hopefully in about four to five months, Welsh will pilot the sub to the bottom of the Pacific Ocean's Mariana Trench, the deepest known point in all the earth's oceans.

The 7-mile ride down is expected to take a little more than two hours, during which Welsh will lie prone in a small, pressurized compartment, with his head lower than his feet. Once on the bottom, the craft can maneuver around like a rover, and Welsh plans to spend about two hours exploring and collecting water and sediment samples before the two-hour ride back.

The potential for discovery is huge, including the possibility that previously unknown forms of life might be found. The sub will be equipped with cutting-edge sonar, but Welsh will also have enough lighting to see up to 200 feet. He's hoping for a show of natural beauty to rival the Aurora Borealis.

"That's the great thing about exploring," he said. "You don't know what you're going to see until you get there."

Other expeditions will follow, including a planned dive by Branson to the Puerto Rico Trench, the Atlantic Ocean's deepest site.

At Welsh's presentation to the nautical museum crowd, questions often dealt with the more mundane aspects of the voyage:

How will Welsh deal with the mental challenge? (His solo plane flying experience will come in handy.) How much will the mission cost? ($7 million to $11 million.) How will he deal with, ahem, sanitary matters? (He'll hold it.)

Welsh fielded the questions in typical good-natured fashion. But I have no doubt that every person in the audience that night shared my astonishment at the man's sheer audacity. No-nonsense guy that he is, Welsh will need those enviable reserves of calm as he sets forth on this great new adventure.

PATRICE APODACA is a Newport-Mesa public school parent and former Los Angeles Times staff writer. She is also a regular contributor to Orange Coast magazine. She lives in Newport Beach.