Geronimo!

"Take a deep breath when you get to the door," shouts my jump master, Monica Olsen, 30. She and Jess Rodriguez, 45, another instructor, yank me off of the floor of the Twin Turbine Super Otter, which has leveled off at 15,000 feet. Staggering under the weight of my 25-pound pack, I scramble half-crouched to the open door. In 30 seconds, I will step out into the cloudless sky above California's Monterey Bay.

I've been on hundreds of flights, though this is the first time I've disembarked in midair. I don't think I'm panicking, but I am numb. And I'm not at all sure how I'll react when I reach the door. Will I freak? Will I freeze? No matter what, there's no going back.

I will be making an assisted free fall, meaning that I'll be sandwiched between Olsen and Rodriguez as the three of us leap from the plane together. As the three of us free-fall at speeds of up to 140 mph, each instructor will have a firm grip on the purple piping of my jumpsuit -- or at least that's the plan.

After about 45 seconds, the jump becomes decidedly unassisted: At 5,000 feet, I yank my rip cord, Olsen and Rodriguez drop away, and I'm on my own. If my main chute gets tangled, I have to launch my reserve chute. If I fall away from the drop zone, I have to steer myself back on course.

I reach the door. An electric-blue sky, like a great gaping maw, opens before me. The Otter is zipping along at a 100-mph clip; the roar of the air at that speed nearly drowns out the drone of the propellers. I clutch the door frame, crouch sideways facing the tail of the plane, and take a deep breath. Then I take another breath. I'm freezing up. Olsen, sensing my hesitation, gets in my face. "Check in, Gina!" I pause for another second, lock on Olsen's eyes, and yell, "Check in!" She nods, giving me a thumbs-up to begin the countdown sequence.

I lean out of the door and holler, "Out!" I pull back into the plane and yell, "In!" And then, as the three of us lean out of the plane, I let go.

Out of the Cubicles and into the Clouds

Once considered an extreme sport, skydiving is working its way into the mainstream. The sport has already had starring roles in such action flicks as Drop Zone and Point Break, and in commercials for Coke and Pepsi. And the number of weekend warriors who are headed skyward is growing by, shall we say, leaps and bounds. In fact, membership in the U.S. Parachute Association, a nonprofit group that promotes skydiving, has nearly doubled during the past 10 years.

But skydiving is still an all-or-nothing proposition. You either land on your feet, or you wind up six-feet under. So why, then, would anyone want to jump out of a plane?

On the surface, sky divers may seem to have some sort of a death wish. But according to one study by Bruce Ogilvie, professor emeritus of psychology at San Jose State University, people who participate in high-risk sports need to seek out ways to live life intensely. Ogilvie found that most risk takers aren't reckless; they're actually very calculated about the risks they take.

The urge to fly may also be hardwired into our DNA. Most of us have wondered what it would be like to be Superman, and we've all had dreams in which we could actually fly.

For Scott Rozic, the 26-year-old CEO and founder of Verge Software Corp., skydiving has a more down-to-earth appeal: He and his employees need to get their heads out of their cubes and into the clouds. Rozic's crew has spent virtually every waking moment during the past 18 months landing clients like Intel and Ernst & Young and gearing up for the launch of Verge's knowledge-management product. "We're sky-diving to celebrate the beginning of our company and the introduction of our first product," says Rozic. "We also want to do something totally fun and different -- and to do it all together."

So the folks at Verge decided to take the plunge at Skydive Monterey Bay. The jump school, just an hour south of San Jose, is a favorite among Silicon Valley code jockeys and VCs. But Rozic had to dodge some interference before taking flight: A week before the jump, Verge's board of directors got wind of the idea and tried to ground its CEO.

"A sense of adventure is what attracted people to Verge in the first place," argues Rozic. "What could be more adventurous than launching a startup? Whether it's extreme skiing or rock climbing or working without knowing whether we'll still be in business tomorrow, it's the thrill of taking on the unknown that keeps us together." Ultimately, that argument convinced the board to let Rozic and his team make the jump. That and the promise that they would never jump again.