Nick Woodman and I are strapped into the cockpit of a vintage racecar on a winding, narrow road in California's Santa Cruz Mountains, taking cliff-side turns at 60 miles per hour and rocketing up to 100 on the straightaways. Strapped to each of our chests are tiny high-definition video cameras. There are two more cameras on the doors, pointing in at us; one over our shoulders, pointing at the instrument panel; one mounted to the dashboard, pointing at my face; one under the nose of the car, to capture the road whizzing by; one attached to the front of the roof; and another looking up over the roof via a pole mounted to the rear end. The car is a Ford GT40, a replica of the legendary vehicle that won the 24 Hours of Le Mans rally race four times in the 1960s. It's the property of GoPro, the company that makes the cameras we're using. Woodman is the CEO and an accomplished amateur racecar driver (and surfer, mountain biker, motorcyclist, and all-around thrill junkie).

We approach a blind turn, and the engine emits a loud brap as Woodman guns it around the corner and down the hill, and the back end of the car fishtails out behind us in a slightly sickening way.

"This car wasn't road-legal until a couple weeks ago—I've never taken it up here with a passenger!" he yells over the engine noise. "I think we need to stiffen up the suspension." Then he hammers the gas again.

I've been trying to stay cool, but my mind is a blur of headlines in the tech press about a wild-man CEO and a journalist plummeting into a ravine to their deaths. I give in after about 15 minutes. "OK, you're starting to scare me," I tell him.

I've given him the sound bite he is looking for—the cameras are rolling, after all—so he slows down a bit, and we cruise the rest of the way through the mountains, through the biker town of Pescadero, and out to Highway 1, where we turn off at Pigeon Point, a clearing near a lighthouse on the cliffs over the Pacific Ocean. A film crew is waiting f...