The west side of the Continental Divide in the Colorado Rockies is home to about half of the ski and snowboard mountains in the state, and a half-dozen of them have built up summer activity infrastructures to lure flat-landers into the mountains.

Several resorts don't run their lifts in the summer -- Powderhorn, Sunlight, Aspen Highlands, Buttermilk -- but remain open for hiking and mountain biking, and general summertime leisure time.

If you're looking for a full-on summer menu, check out Telluride. On and off the mountain, there's plenty to keep young and old busy -- from via ferrata to bike parks to kids camps to rafting and Jeep tours. Highlight on the hill is Canopy Adventure, a tree-top complex of zipline, aerial bridges and rappels that begins with ride up the Village Express chair.

At Purgatory, MTB-focused lift access, trail prep and downhill challenges are the norm. The first U.S. resort to host a MBT world championship (1995), "Purg" sells single-ride, day, and season passes-- the latter includes massive Spider Mountain bike park in Austin, Texas.

Another mountain bike mecca is Crested Butte. Its Mountain Bike Park opened in 2009, and its more than 30 miles of single track downhill and X-C runs have been improved ever since. The bike-friendly Red Lady Express does the heavy-lifting to get riders onto the mountain.

Steamboat hosts a ton of attractions around its under-construction base area. Featured is the Outlaw Mountain Coaster with a descent of more than a mile long. With that length, there's plenty of track for loops, turns and twists.

Aspen Mountain and Snowmass crank up their gondolas for summer visitors. A ride up the Silver Queen gondola reaches the11,212-foot summit of Aspen Mountain. The summit area has been developed as the main magnet for the resort, with hiking trails, wildflowers, live music, good food and 360-degree views of Maroon Bells and Roaring Fork Valley.

Across the way, Snowmass turns on a gondola of its own -- the Elk Camp Gondola -- to get folks to the trails, vistas and food in and around mid-mountain Elk Camp. New this summer is the Lost Forest Adventure Center at Elk Camp, with ziplines, bike trails, climbing wall and mountain coaster.

Winter Park is playing off on the popularity of e-bikes this summer with 90-minute tours for pedal-assist mountain bicycles. Three tours run daily from the top of the Explorer Express chair at Sunsport Lodge (also headquarters for renowned Trestle Bike Park). E-bikers head up another 600 feet of vertical to Lunch Rock. No charge for views of Continental Divide.

The Indy Pass has finally signed up a Colorado ski and snowboard mountain -- Sunlight Mountain -- so it may be a good time to pair it up with another of old-school, Western Slope day-trip resorts, Powderhorn..