Lion's Lair - Trail Running

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One of Boulder’s newest trails, Lion’s Lair is also one of the city’s best. The smooth dirt trail boasts breathtaking views, a perfect grade, and a relief from the congestion of nearby Mt. Sanitas.

Written by

Matt Wesson


2.2 miles

Lion’s Lair climbs 2.2 miles from Sunshine Canyon to the summit of Mt. Sanitas. Runners can easily add on the Sunshine Canyon Trail and the Mount Sanitas Trail for a 5.3 mile loop.

Destination Distance From Downtown

2.3 miles


3 of 5 diamonds

With 780 feet of elevation gain, Lion's Lair is a solid trail run. It is a well-graded and maintained path with ample switchbacks.

Time To Complete

0 hours

The 2.2 mile trail should take 30 minutes or so to ascend at a conservative uphill pace. That time is easily cut in half for the speedy downhill.


All Seasons

The trail is well maintained and available year round.

Dog Friendly


Dogs are not allowed on this trail.

Fees Permits




Still new and relatively undiscovered, Lion’s Lair is a 2.2 mile point-to-point trail from Sunshine Canyon to the summit of Mount Sanitas. It is one of the very best trail running options in Boulder, as RootsRated described when the trail first opened. You can also take the Sunshine Canyon Trail to the trailhead and the Mount Sanitas Trail down from the summit to create a terrific 5.3 mile loop. RootsRated 

What Makes It Great

Completed in 2014, Lion’s Lair is one of the most immaculate trail runs available in Boulder. With no bikes or dogs allowed, a moderate grade, and interval style inclines and rests, it’s clear that this trail was designed with runners in mind. Lion’s Lair climbs 2.2 miles to the summit of Mt. Sanitas and covers 780' of elevation gain along the way. However, the quality of the trail makes the accent more than manageable and the decent easy on the legs. You can fly down this trail at top speeds without having to worry about snagging a toe on a rock or root. There are no dogs allowed on the trail, which is one drawback for some, but is understandable given the bear and mountain lions known to roam this area. 

Compared to the always-busy Mount Sanitas Trails on the east side of the mountain, Lion’s Lair feels strikingly remote. The transition from those well-trafficked trails to the west side of the mountain can be jarring. You feel like you’ve left the city miles away and are truly in the backwoods, with all the beauty that entails. The trail transitions through some of the best views Boulder has to offer, including the Indian Peaks, rolling meadows, and waving pines that keep the trail shaded most of the way. 

Who is Going to Love It

Trail runners looking for a smooth, clean mountain running trail will be hard pressed to find a better option than Lion’s Lair. With incredible views, a brand new trail, no bikes allowed, and minimal traffic, Lion’s Lair is the type of trail that runners dream about. It's also a nice trail for hikers wanting to take in a new aspect of Mount Sanitas. 

Directions, Parking, & Regulations

There is a trail spur at a sharp curve in the road along Sunshine Canyon. The trailhead is about 1.8 miles west of the intersection of Mapleton Avenue and 4th Street. However, I would recommend parking at the Centennial Trailhead where there is more parking, and taking the Sunshine Canyon Trail up to Lion’s Lair. The Sunshine Canyon Trail ends at a residential driveway. There you can cross the road into the adjacent residential driveway and you will see signage for Lion’s Lair on the uphill side. You can continue up the trail from there.


Lion's Lair Trail

Boulder, Colorado, 80302
40.034037, -105.315788

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