Rock climber Alex Honnold made headlines in June when he climbed 3,000 feet to the top of Yosemite’s El Capitan without a rope. But long before he stepped onto those granite cliffs, Honnold, like many of today’s leading climbers, first learned his sport in an indoor climbing gym.

Once regarded as an extreme sport, climbing has exploded in popularity in recent decades, thanks in part to the 400 such gyms across the U.S.

Even for people who would — quite wisely — steer clear of the kind of adventure Honnold pursues, rock climbing provides a bonanza of benefits from physical fitness to mental training to camaraderie.

And indoor climbing offers those benefits year-round, with air-conditioning, cushioned floors and everything climbers need to have fun and stay safe — including ropes.

Arizona’s first climbing gym, Phoenix Rock Gym in Tempe, will celebrate its 25th anniversary in August, and the Valley has gained several other gyms in recent years. They feature climbing lessons for adults as well as recreational clubs, competitive teams and summer camps for children. Many offer yoga classes and even Ninja Warrior-style fitness training. They rent climbing shoes and harnesses; host competitions; and provide a fun option for birthday parties and corporate team-building.

Although each gym is unique, they share some basic qualities. All feature rugged walls supported by steel framing and faced with either wood or fiberglass, which is coated with a textured paint to provide grip. The walls are shaped with angles, curves and overhangs that simulate natural rock features, but the color-coded climbing routes are created with plastic holds.

All of the gyms feature beginner walls with large, closely spaced holds to help new climbers get comfortable. All provide training in how to fall and belay safely.

And all of them offer entertainment and exercise perfect for all ages — and any time of year.

Phoenix Rock Gym

When Paul Diefenderfer first heard about indoor climbing, he thought it was a stupid idea. An avid rock climber since the 1970s, he couldn’t imagine how an artificial wall inside a climate-controlled building could provide the same exhilaration and adventure.

But in 1991, Deifenderfer was cajoled into visiting a rock gym during a trip to California.

“It blew my mind,” he remembered of the experience. “Somehow it captured the essence of climbing, but made it totally accessible. I went from thinking it was ridiculous to deciding that I had to open a climbing gym.”

Diefenderfer and a friend scraped together $20,000 and opened Phoenix Rock Gym in Tempe in August 1992.

At the time, climbing was still a fringe sport, and there were no other gyms nearby to use as models. Tempe’s city building inspectors argued about how to handle the permits. But Diefenderfer was confident his strange new business would draw people in.

“We figured we’d teach everyone we knew how to climb and they’d come, then they’d bring their friends, and so on,” he explained. It wasn’t much of a marketing strategy, he now admits, “but it worked!”

Diefenderfer bought out his friend a few years later and, in 2000, built an even larger facility with 30-foot walls and 17,000 square feet of climbable terrain.

By now, the gym has welcomed more than 300,000 people, ranging from casual visitors to hard-core mountaineers.

“We get everybody,” Diefenderfer said. “I’ve heard people call us the ‘Cheers’ of climbing gyms, which is great. People come here knowing they’ll find friends, even if it’s their first time. And we encourage that. Our goal is to promote fun.”

AZ on the Rocks

Fun is also what spurred brothers Kevin and Kent Berk to open AZ on the Rocks in north Scottsdale. Kent was vacationing with his family when rain canceled their outdoor plans and, desperate for something to do with three wiggly children, he discovered a climbing gym. None of the family members had climbed before, but they loved it so much that the brothers wanted to build their own gym.

The Berks aimed to make AZ on the Rocks as family-friendly as possible, with programs for all ages and special events for holidays. But because they didn’t know much about the sport, they hired experienced climbers like manager Stephanie Mills, who started work the day the gym opened and continues to welcome new climbers.

“Climbing is such a great form of exercise,” Mills said. “People love that they can work out without having to ‘work out’.”

AZ on the Rocks opened in 2004 as a spacious facility with 31-foot-high walls, plus features like a bouldering section, auto-belays for children and solo climbers, a separate area for fitness and yoga, and a dedicated party room.

Many gym members are already part of the Arizona climbing community, Mills said, but even when people get on the walls for the first time, she wants them to feel the same joy that inspired the creation of AZ on the Rocks.

“We’re totally inclusive,” she said. “We’ve had 18-month-old kids, and we had an 88-year-old great-grandmother who came here for her birthday. And she loved it.”

Ape Index Rock Climbing Gym

Across the Valley, Amos Cox tries to foster a similar sense of community at Ape Index in Peoria. A longtime outdoor climber and guide, Cox built his West Valley gym in 2008 to blend the challenge of outdoor climbing with the convenience of an indoor setting — and to have fun.

One of the largest gyms in the area, Ape Index has walls that reach up to 38 feet high and are textured much like real rock — if rock came in Day-Glo colors. Playful features include a 32-foot-diameter globe that lets climbers step from Argentina to Brazil, a stalactite-like tower with routes that spiral around the sides, and giant soda cans with names like “Dr. Crag.”

The bouldering area includes a climbable tunnel between the first and second floors, and an additional, members-only bouldering area is set with competition-style routes for more serious climbers.

But, regardless of experience level, manager Aidan Jacobson said the goal at Ape Index is to break down barriers to the sport.

“For the longest time, climbing was a mentor-student thing,” Jacobson explained, “where you could only learn by finding someone who would teach you a little at a time. But at the gym, you can come in here with a 2-year-old and we’ll get you climbing in a few minutes.”

Focus Climbing Center

Joe Czerwinski knows firsthand how climbing gyms can break down barriers. In 1992, the Arizona native was hiking Camelback Mountain when one of his buddies suggested they could climb the rock formations.

His response?

“I said: ‘I don’t know; I don’t think that sounds safe.’ “

A few months later, the friend mentioned a new place called Phoenix Rock Gym. It was indoors and provided all the safety equipment a nervous athlete could want.

“We went the next week,” Czerwinski remembered, “and that was the day I got sucked into rock climbing.”

Czerwinski was sucked in so thoroughly that he became a route setter and worked for the X Games in the U.S. and Asia. He started competing and landed on the U.S. National team as a team member, then coach.

And, in 2013, Czerwinski opened Focus Climbing Center in Mesa.

A bright, open space, Focus features a bouldering wall that reaches as high as 18 feet and a 28-foot wall for roped climbs. The floor, made of a 2-foot-thick gymnastics cushion, not only catches falls but doubles as a giant couch to rest on and socialize between routes.

Although Focus hosts frequent competitions, Czerwinski said he puts more emphasis on the social aspect of climbing than on winning contests.

“To me, climbing is about coming together with your friends and supporting each other,” he explained. “Some people have called this gym ‘the fun frat house,’ and I like that.”

Black Rock Bouldering Gym

At the same time the Valley’s oldest rock gym hits the quarter-century mark, the newest will celebrate its first birthday. Chris Dodge opened Black Rock Bouldering Gym last August in a former ice rink in Phoenix.

Dodge himself remembers attending birthday parties at Phoenix Rock Gym as a kid. But he didn’t start climbing regularly until he was in the Army and, seeking a way to stay fit without getting bored, he discovered indoor bouldering.

In addition to the physical exercise, Dodge loved the mental clarity of climbing and the way it took him away from the stress of military life.

“When you’re climbing, you can’t do anything else,” he explained. “You can’t worry about anything. You can’t zone out or you’re off the wall.”

After returning to civilian life, Dodge set out to create a space that would help other people find a similar serenity. Because he prefers the simplicity of climbing without ropes, Black Rock is dedicated to bouldering. The gym currently has 5,000 square feet of walls, but Dodge plans to add more walls next year for his rapidly-growing membership base.

“Originally, I thought I’d just get really dedicated climbers who wanted additional training, but I’ve also gotten a lot of beginners, which is great,” he said. “When we get first-time visitors, the first thing we do is give them a high five. And then we teach them how to be safe.”

“Climbing is wild by nature,” Dodge admitted, “so we’re trying to present climbing in a somewhat controlled environment.”

And, considering the weather outside right now, a controlled environment sounds like a pretty good place to start climbing.

Indoor climbing gyms

PHOENIX ROCK GYM: Bouldering, top rope and lead climbing with walls up to 30 feet. Offers day passes and memberships. Gear rental, private lessons, yoga classes and lead classes. Climbing team and summer camp for children. Hosts competitions, birthday parties and corporate events. 1353 E. University Drive, Tempe. 480-921-8322,

AZ ON THE ROCKS: Bouldering, top rope and lead climbing. Ten auto-belays. Offers day passes and memberships. Fitness center with Ninja Warrior course and coaching available. Gear rental, private lessons, yoga classes and lead classes. Climbing team and summer camp for children. Hosts competitions. Private room for birthday parties and corporate events. Zip-line and freefall experience for special events. 16447 N. 91st St, Suite 105, Scottsdale. 480-502-9777,

APE INDEX ROCK CLIMBING GYM: Bouldering, top rope and lead climbing. Offers day passes and memberships. Fitness equipment. Gear rental, private lessons and lead classes. Climbing club, team and summer camp for children. Hosts competitions, birthday parties and corporate events. 9700 N. 91st Ave., Peoria. 623-242-9164;

FOCUS CLIMBING CENTER: Bouldering, top rope and lead climbing, with auto-belays for top rope. Offers day passes and memberships. Fitness equipment. Gear rental and private lessons. Preschool climbing classes, summer camp for grade-school children, climbing team for children and youth. Hosts competitions, birthday parties and corporate events. 2150 W. Broadway Road, Suite 103, Mesa. 480-718-5258;

BLACK ROCK BOULDERING GYM: Bouldering. Offers day passes and memberships. Fitness center with weight-lifting and cardio equipment, slackline, and Ninja Warrior course. Gear rental, private lessons, and yoga classes. Climbing team and summer camp for children. Hosts competitions, birthday parties and corporate events. 10436 N. 32nd St., Phoenix. 602-843-2724;

CLIMBMAX CLIMBING GYM: Top rope, lead and bouldering. Offers day passes and memberships. Fitness equipment. Gear rental and private lessons. Climbing team and summer camp for children. Private room for birthday parties and corporate events. 1330 W. Auto Drive, Suite 108. Tempe.  480-626-7755;

Other climbing facilities

LIFETIME FITNESS: Health and fitness club including climbing wall for member use. Locations in Tempe, Gilbert, Scottsdale, North Scottsdale, Goodyear.

ABILITY 360 FITNESS CENTER: Fully accessible fitness center including a climbing wall with adaptive climbing. 5031 E. Washington St., Phoenix. 602-386-4566;

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