I am no stranger to the occasional adrenaline rush. I am known to enjoy hurtling down class IV and V white water, poised and paddling at the front of the raft. I love it. I know the dangers. I have a healthy fear of and respect for the river. I really love it. But rock climbing? Surely we can all agree that's a sport for lunatics. You've seen themÉlean-muscled Spiderman-wannabes clambering up sheer rock faces at the Pinnacles or Garrapata (more and more each year), simply to turn around and head straight back down again. To a certified acrophobic (i.e., me), it sure looks like bizarre behavior. But maybe I'm wrong. I began to wonder if my head could be turned. In my research, I came across this quote from Victorian-era rock climber Alan Harkinson: "Rock climbing is a sport that demands complete concentration, and calls into play almost the whole of a man: his muscles, balance and nerve; his courage and his mental self-control. It makes two basic challenges: the simple physical challenge presented by steep and difficult rock routes, and the subtle, subjective challenge of retaining the power to behave coolly and sensibly in hazardous situations. Its rewards are a sense of fitness and well-being, the pleasures of companionship and achievement and, above all, the feeling of being intensely alive." Interesting. Since questioning Harkinson was quite clearly out of the question, I sought to find one of his modern-day, geology-conquering descendants. I wound up at Sanctuary Rock Gym in Sand City. Toto, we're not in Kansas anymore. I walk into the gym for my meeting with Spike, the climber whose life's labor of love is Sanctuary Rock Gym. His office is a disheveled shrine to rock climbing: gear, pictures, climber-wear, gadgets and, of course, a route map of El Capitan in Yosemite. He has been enchanted by the siren song of rock climbing for more than 13 years when he embraced this form of adrenaline rush right down to an atomic level. From talking to the avid climbers that I met, I learned that his is not an uncommon story. Love at first height. Kids are going crazy for it, too. Stop into Sanctuary any weekend day and you're bound to find quite a few scrambling up and down the walls. Hey, it beats the monkey bars any day! Sanctuary's summer day camps are filling up fast, too. Brian Popovich is a 15-year-old rock climber from Seaside who spends every moment he can at Sanctuary. He was introduced to rock climbing a year-and-a-half-ago by a Scoutmaster (rock climbing is a new Boy Scout merit badge) and hasn't stopped since. He is at the gym every day and gets to climb in the great outdoors maybe once a month (it's a little more difficult to get to the Pinnacles when you're too young to drive). He's even gotten a couple of friends interested, but it sounds like he's the one with the real jones. Does he get scared? "Occasionally you get the fear jolt, but that's what you're looking for. Fear is healthy. Without fear, it would be dangerous to climb." Just as Alan Harkinson was in his time, today's climbers are enrapt by the adrenaline rush, the physical challenge and most of all, the mental challenge of problem-solving that accompanies every move. Rock climbing has been hugely popular in Europe for some time. Professional climbers there are well-known star athletes. Although intrepid American climbers have been ascending sheer rock faces back to the John Muir days of Yosemite, it wasn't until the first rock gyms started to open in the late 1980s that the sport experienced the astronomical growth in popularity that brings it to today's level of visibility. Working out in a rock gym is a gateway drug to the harder stuff. Just check out the Pinnacles on a spring or fall weekend. The designated rock climbing areas can resemble a renegade troupe of Cirque du Soleil with the climbers' colorful apparel and the acrobatic physical agility on display. If you can't get out to the Pinnacles to gauge the popularity, just type in "rock climbing" at your favorite Internet search engine. You'll find a towering list of Web sites dedicated to and written by those spellbound by the sport (Find Sanctuary at www.rockgym.com). Intricate maps and ratings of climbing routes. Lists of injuries common to climbers. Rock gyms. Places to buy gear. Diaries of particularly excellent climbs. Even dorky photos. I asked Spike if, with the burgeoning popularity of the sport, he feared desecration of popular sites. He wasn't concerned. "Rock climbers are, in general, more conscious about affecting the areas they climb." Most conscientious climbers belong to the Access Fund, a national non-profit dedicated to preserving and protecting climbing areas. Getting outside of Sanctuary Rock Gym in Sand City and Pacific Edge Rock Gym in Santa Cruz, you'll find yourself driving just a bit to touch real stone: Pinnacles National Monument, Garrapata and Granite Canyon are noted local sites. Then there's the wall below the Bath House at Lovers Point-even though it'll probably cost you a ticket courtesy of the Pacific Grove Police Department to attempt that. But heck, a fine won't necessarily stop the intrepid, jonesing rock climber. Within three and a half hours' drive, Yosemite is the best place. If you're willing to venture out five hours, you can get to a real mecca, the Eastern Sierras near Bishop (yes, the famous home of Mule Days). The local climbing sites rate fair to middling in comparison with statewide sites. "The Pinnacles is a good place to learn," says Spike. "It's loose. It's scary. It teaches you to climb gently and the protection is good. We just got our guiding permit for the Pinnacles and will start guiding out there in the fall." He described to me climbing at the Pinnacles, watching the soft stone hand holds bend in his grasp. Yikes. Garrapata is more of a bouldering site. That means there are no ropes and you're closer to the ground, but it requires more power to accomplish the harder, more gymnastic moves. Granite Canyon is more of top-roping area. So, now maybe you're starting to feel that itch. It actually sounds good to get high-high up, that is. It's probably best to get started in a gym like Sanctuary Rock Gym where you can learn all the basic skills in a safe environment with certified instructors. In about three months, you would then be ready to progress to real stone, but with an experienced guide. It's also easier on the pocket book to start in a gym. To get set up with your own gear to climb in a gym will cost you on the order of $200 (not including day use or membership fees). To be fully outfitted for outdoor climbing, think somewhere in the $1,000 to $3,000 range. Better test it out at the lower end. So, after all this talk of rock climbing and climbing gyms, even this acrophobic is considering giving it a go. The avid climber's passion for this way of life is infectious. When I first started writing this, I thought not a chance in h-e-double toothpicks. But after all, if I can tackle raging white water at 3,700 cubic-feet-per-second, why not jutting, jagged, primordial monoliths with soaring height and unforgiving faces? I'll get back to you on that one.