In 1990, Amelia Rudolph was hiking through Tuolumne Meadows, a stunning mountain pass in Yosemite National Park, when she had an epiphany on a shiny granite bluff: “Could you make a performance here?” she wondered. “Could you dance on a cliff?”

Rudolph, a dancer in the Bay Area who trained with Hubbard Street Dance Chicago, had just written her college thesis on dance and ritual and recently become an avid climber. Those experiences converged in her mountaintop revelation — and inspired her to make a dance while dangling from the climbing wall at the gym where she worked.

That dance, though unrefined, was enthusiastically received. “I realized I tapped into some part of our human imagination that loves to fly,” Rudolph, 61, said in a phone interview.

From that seed grew Project Bandaloop, now just Bandaloop, a vertical dance company that fuses contemporary dance with climbing technique and technology. Using equipment, like harnesses, ropes and belay devices, Bandaloop can take dance’s soaring, ethereal qualities to extremes and bring them to unlikely perpendicular surfaces like the rock face of El Capitan in California or Tianmen Mountain in China.

“The spirit of the company,” Rudolph said, celebrates “the power and vulnerability of natural spaces.” (The group performed at the University of Denver’s Newman Center in 2022.)

Now Bandaloop’s gravity-defying movement and ecological DNA have come to Broadway in the musical “Redwood,” starring Idina Menzel, which opened Feb. 13.

At a rehearsal a few weeks earlier at the Nederlander Theater, Menzel was on a platform, in a harness, a dozen feet off the ground in front of an enormous tree trunk — the set’s dramatic visual centerpiece — preparing to step into the air during a song about release.

“Try coming off the platform with a sense of float,” said Melecio Estrella, Bandaloop’s artistic director, from below.

Menzel leaned forward and was suddenly swinging freely. She hugged the trunk then pushed off into a gentle spin. Estrella encouraged her to find more buoyancy by landing back on the tree in plié — a typical dance note, except she was sideways, and singing. (Estrella is credited with the show’s vertical choreography, and other Bandaloop members contributed to rigging design, risk management and wellness.)

In rehearsal, she again propelled herself from the tree, now into a backflip, achieving a suspended weightlessness that Estrella called “loft” — a central ingredient in vertical choreography that’s enhanced by the distance of a dancer from her anchor. (So the taller the dance surface, whether fake redwood or skyscraper, the more loft.)

Loft was one of the core movement principles that Rudolph identified as she was establishing her company in Berkeley in the 1990s with the goal of bringing together sport, art, nature and dance.

“We spent a lot of time innovating and building technique,” she said. In particular, she drew from the “mentality of climbing, where you’re moving through terrain quickly and safely and in a light way.”

Without a permanent studio until 2003, Bandaloop rehearsed wherever it could — climbing gyms, rented walls at the nearby university, even the side of a highway, where a police officer once asked Rudolph what she was doing.

She replied, “I’m developing a dance form.”

There was some precedent. In 1970, Trisha Brown, the pioneering postmodern choreographer, presented the now-celebrated piece “Man Walking Down the Side of a Building.” And Northern California, where Rudolph lived and worked, was also home to other dance artists working above the ground, like Joanna Haigood and Jo Kreiter.

But Bandaloop stood out because of its sense of scale, drama and artistry, and it attracted high-profile commissions. A dance on the Space Needle in Seattle for the Bumbershoot Festival in 1996 raised the troupe’s visibility. Later, the group worked with Pink on her performance at the American Music Awards in 2017 and danced on St. Paul’s Cathedral in London, in 2023.

“Bandaloop has had incredible opportunities that most dance companies don’t have,” Rudolph said, “because we have the ‘wow’ factor.”

But that wow factor, its whiff of spectacle (a word she likes to avoid), means Bandaloop hasn’t always been embraced by traditional dance presenters who tend to program for proscenium stages.

So the company embraced nontraditional collaborations, like municipal partnerships and corporate work that came with bigger paychecks. “We will cross into that world and learn from it,” Rudolph said. “We gain from it economically and then feed it back into the art.”

That money helped the company put down roots in Oakland in 2007, where it recently signed a 20-year lease on an expanded 8,000-square-foot, light-filled studio, allowing it to increase its educational offerings and introduce more aspiring performers to its distinct style. (In 2020, Rudolph handed the Bandaloop reins to Estrella, an environmental activist and longtime dancer in the troupe. She remains a board member and leads ad hoc projects.)

When Estrella joined Bandaloop in 2002 from the contemporary dance world, he had never been on a climbing wall. “I didn’t really know what I was walking into,” he said.

But he was attracted to the group’s thrilling physicality, as well as its melding of art, nature and politics. He grew up in Sonoma County among trees — his aunt’s front yard had three giant redwoods. “Those are the forests that I played in as a kid,” he said.

As a teenager, he became involved in environmentalism, learning about direct action and how to support tree sitters. This was around the time when Julia Butterfly Hill lived in a redwood for more than two years to protest logging. (Her story partly inspired “Redwood,” and it briefly figures into the show.)

With Bandaloop, Estrella found a company in which dance and activism have long been intertwined. Bandaloop has created many works and community events promoting environmental stewardship, partnered with national parks, and recently engaged a consultant to evaluate its climate footprint. The company has also shared its technical and artistic expertise with climate activists and organizations like Greenpeace and Save the Redwoods League, imparting its safety protocols and advising on style, including what to wear and how to climb with flair to attract media attention.

“Let’s talk about costuming, let’s talk about color, let’s talk about the movement of dance,” said Thomas Cavanagh, an environmental activist who began as a Bandaloop rigger in 1998 before serving as its operations and technical director, and, since 2012, its executive director.

Bandaloop’s ecological values and showmanship made it an obvious fit for “Redwood,” about a grieving woman who finds connection in a forest and solace high in a towering tree. But the show’s director, Tina Landau, was unaware of the company’s activist roots when she first reached out. She was simply drawn to the poetry of the group’s work.

“They really understood and captured what I’m attracted to in the metaphor of flight,” she said. Later, she realized they were “kindred spirits” in their worldview as well.Since the “Redwood” premiere, the company has been developing a site-specific work called “Flock,” the final part of a trilogy addressing the climate crisis. “Part of what we have to deal with right now in climate is our grief,” Estrella said of the work.

Considering such existential issues, he says he often wonders why it’s important to bring audiences together around art. “For me, it’s great purpose is to have a place to feel.”