Can't help but smile when completing a route at Momentum's new digs. Image: Jon Vickers

In a city of firsts—first Starbucks, first grunge, first place to make socks and sandals a fashion statement—here's one you may not know: Seattle is home to America's first climbing gym, Vertical World. More than 30 years later, the indoor spaces have proliferated across the region; now a new gym devoted to bouldering opens in SoDo Saturday.

Momentum Indoor Climbing is a chain with six locations around Utah and Texas, and the SoDo space will be its first Seattle location. The focus is similar to that of Beacon Hill's Seattle Bouldering Project; bouldering is a kind of climbing done without ropes, on shorter walls. But that doesn't mean it's necessarily easy. The routes, also called problems, can require intricate and difficult skills.

Momentum opens with 7,000 square feet of bouldering space. Image: Jon Vickers

The new 19,200 square-foot Momentum space, a former Sears Auto Center next to Home Depot on First Avenue, has a cardio room, yoga space, and weight room. There's even a section near the entrance displaying local art. Owners hope to eventually open a snack and drink bar inside.

The gym uses Walltopia walls, which emphasize a 3D shape for climbing and offer a high density of routes on every surface. Handholds are periodically rearranged on the wall to form routes, and the people who design them are experts at planning how a person can move up the wall. Momentum brought in Mark Mercer from Florida, a former director of route setting for Aiguille Rock Climbing Center and route setter for USA Climbing, and Moé Corbett, an experienced competitive climber.

The multicolored holds may make the indoor gym look like a rainbow, but they are meant to mimic actual rocks. "Momentum creates routes that are fun and exciting, but also mirror a realistic climbing style outside," says operations director Chris McFarland. What isn't the same as the great outdoors: the pads that line the floor. They create a soft landing for anyone coming off the wall—either on purpose or by accident.

Saturday's grand opening will kick off with a ribbon-cutting ceremony at 9am, followed by free climbing until 11pm. A live DJ, food truck, and beer bar will liven the big event, and demo climbing shoes are provided by Mad Rock Climbing. The opening is the first sign of Momentum's, well, momentum: The chain plans to open a rope gym in early 2019—a block from Seattle Bouldering Project.