The zany joy of ziplining catches hold in the USA

ROCKWOOD, Colo. -- Debbie Burns' 55-year-old knees are quivering as much as the aspen trees that blanket the surrounding San Juan Mountains.

But to Burns, perched at the edge of a two-story-high platform wrapped around an old-growth ponderosa pine, her grandson's happiness trumps an aversion to heights so acute she once had to be shoved off a chair lift.

So after watching 11-year-old Colby Moe swoop down the first of nearly two dozen steel ziplines strung across the Tall Timber Resort in southwestern Colorado, the vacationer from Bakersfield, Calif., takes a deep breath — and her own 72-foot-long leap of faith.

"Oh, my gravy!" Burns yells, accepting a congratulatory hug from Colby after gliding to a graceful stop at the next tree. "Now, can I stay here and keep doing the bunny-hill version?"

Not a chance.

Transcending fear is part of the fun at Tall Timber's Soaring Tree Top Adventures. Opened four years ago and tagged by TripAdvisor.com as the USA's most popular attraction based on reader rankings, it's a leading example of a high-wire act that's taking off like Tarzan.

The adventure of strapping into a harness, clipping to a cable, then zipping across a canyon, down a mountain or through a canopy of trees — hence the terms ziplining and canopy tours — was popularized in Costa Rica a decade ago. Now, the elevated excursions are cropping up across the USA, with at least two dozen in operation and dozens more in the works.

Some, like an Alaska zipline that whisks cruise ship passengers more than 1 mile in 90 seconds, are aimed at adrenaline junkies. Others cater to families wanting to both scream and savor the scenery.

Many canopy tours let participants "connect with nature and each other in an otherwise inaccessible environment," says John Walker of Bonsai Design, a Grand Junction, Colo.-based company that has designed seven U.S. zipline courses over the past three years.

That mission certainly applies to Soaring Tree Top Adventures.

Tall Timber owners Denny Beggrow and his son Johnroy created the 5½-hour aerial tour as a way to broaden their remote, 180-acre retreat's appeal. Inspired by Johnroy's childhood treehouses and Sean Connery's rain-forest adventures in the 1992 film Medicine Man, their tour rapidly eclipsed such offerings as fly-fishing and horseback riding among wealthy patrons that have included CEOs, movie stars and vice presidents.