- Length: 4.4 miles roundtrip
- Difficulty: Moderate
- Why we love it: This peaceful trail is so well graded that you barely feel the 800-foot elevation gain to the summit of Mount Sanitas.
- When to go: Any time you crave sweeping views but don’t want to work too hard for them
- Pre-hike buzz: Just after you exit US-36, stop by the family-operated Brewing Market in Basemar Plaza for pastries and freshly brewed coffee.
- Restrooms: None; the closest option is at the Centennial Trailhead at the mouth of Sunshine Canyon
- Dogs: Not allowed on this trail
In stark contrast to the steep, exposed, and very popular east side of Boulder’s Mount Sanitas, the Lion’s Lair is a lesser-known “back door” route to the same rocky summit and gorgeous panoramic views. Although this trail climbs about 800 feet, it is so well graded that it feels significantly easier than the 1,100-foot climb up the eastern side. The tall Ponderosa pines and rocky granite boulders also offer some shade and relief from the wind, making this trail a great choice on warm and/or windy days.
From the trailhead, which is located on the north side of the parking area, follow the short, 0.2-mile spur up to the junction with the Lion’s Lair Trail. Turn left here and follow the path as it climbs steadily through the forest for 2 miles. As you hike, keep an eye out for frisky Abert’s squirrels, recognizable by their black color and tufted ears, as well as other wildlife, including the occasional black bear or mountain lion, for which the trail is named.
As you near the top, the trail levels out and bends toward the south before ascending the final summit ridge. There are a few great picnic spots up here, including the summit, where you’re treated to awesome views of Boulder and the Great Plains stretching to the horizon.
This trail can either be hiked as an out-and-back or as part of a 5-mile loop that includes the Lion’s Lair, Sunshine Canyon, and Mount Sanitas trails. If you choose to do the entire loop, it’s best to park at the Centennial Trailhead at the mouth of Sunshine Canyon. If you prefer steep ascents, hike it counter-clockwise; if instead you enjoy steep descents, follow the loop clockwise.
Getting there: From Denver, take I-25 north to US-36 west to Baseline Road. Turn left onto Baseline and follow for 0.4 miles to Broadway. Turn right onto Broadway and follow for one mile to University Avenue. Turn left on University and then, in 0.3 miles, turn right onto 9th Street and follow it for 0.7 miles to Mapleton Avenue. Turn left onto Mapleton and follow this road, which turns into Sunshine Canyon Drive, for about 2 miles to the first hairpin curve, where there is limited parking.