Unveiling the Lion's Lair Trail on Mount Sanitas

James Dziezynski
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In late autumn of 2014, the city of Boulder quietly transformed a “locals only” hiking path that went from Sunshine Canyon to the summit of Mount Sanitas into an official open space trail, aptly named Lion’s Lair. Twice, I had to reschedule my efforts to map the trail because it was closed for recent mountain lion kills—it quickly lived up to its name.

There are three things that define this beautiful, wild trail:


  • It’s the smoothest, cleanest mountain running trail in Boulder by far; absolutely perfect for runners. A moderate grade, meticulously smooth, alternating inclines and rests, and the descent is easy on the knees. This makes it a great descent trail for runners no matter which way you go to the top.

  • No dogs are allowed. A bit of a bummer for us dog lovers, but understandable as the western side of Mount Sanitas is pristine.

  • This is a truly wild trail, despite only being a mile from town. On my first hike I saw Abert’s squirrels (black squirrels with tufted ears, rarely seen on the east side of Mount Sanitas), mountain lion tracks, and a pair of black bears lumbering on the hillside.

In contrast to the busy, east-facing Mount Sanitas Trails , Lion’s Lair immediately plunges into the deep wilderness. Gone are the expansive eastern views of the city, replaced with vistas of the rolling hills of Sunshine Canyon and the majestic Indian Peaks on the western horizon. Crooked pine trees quiet the wind and provide shade as the trail gradually climbs up a series of switchbacks. The trail developers did an excellent job designing this route, seemingly with trail running in mind (pack training and simple day hiking is also encouraged). This would also be one of Boulder’s fastest, sweetest mountain bike trails—if bikes were allowed on it. No bikes, no dogs.

Lion’s Lair goes roughly 2.1 miles to the summit and covers 780 feet of elevation gain. Along the way, there are open meadows, incredible views, neat rock formations on the summit ridge (with some serious bouldering potential), and a quick traverse over the “true” summit of Mount Sanitas at 6,863 ft. The “hiker’s summit” is 6,816 feet. The views of the Indian Peaks along the way are just as good, if not better, than the hiker’s summit views. As you near the top, the “classic” eastern views come into focus as well.

It's like this all the way up! Smooth and never too steep.
It's like this all the way up! Smooth and never too steep. James Dziezynski

If you visit Lion’s Lair solo, it would be wise to wear a bear bell to announce your presence. Wildlife photographers should check out this trail as well—I wasn’t even trying to spot critters and had a great show! This may become Boulder’s most popular mountain-based trail running path in the future, but for now the crowds are low and the trail is serene, almost to the point of being spooky. Lion’s Lair is a welcome addition to the city’s network of trails that aims to minimize impact the wildlife that has called the western side of Sanitas home for years.

Looking south from the summit of Mount Sanitas.
Looking south from the summit of Mount Sanitas. James Dziezynski

Directions and Beta

The preferred trailhead is in a sharp bend in the road along Sunshine Canyon with room for about 5 vehicles. From the intersection of Mapleton Avenue and 4th Street, go west on Mapleton Avenue 1.8 miles farther and park on the right side of the road just before the canyon road gets steep. You will bypass the Centennial Trailhead and Mapleton Avenue will turn into Sunshine Canyon Drive. The trail begins to the north of the parking area, and there is a signpost, along with the start of the smooth, flat trail.

Parking for the Lion's Lair Trail along Sunshine Canyon. This is 1.8 miles from the intersection of 4th and Mapleton.
Parking for the Lion's Lair Trail along Sunshine Canyon. This is 1.8 miles from the intersection of 4th and Mapleton. James Dziezynski

The Lion’s Lair Trail is easy to follow, though the fork where the connector trail is not currently marked. If you are on the main trail, stay left and continue uphill. There is one more marked “neighborhood access” trail as well. Towards the summit ridge, there are a few sidepaths that simply loop around a few of the rock obstacles. Just before the hiker’s summit, there’s an old “local’s” trail that connects with the Mount Sanitas Trail as well. These are easy diversions to explore.

Trail runners rejoice, your knees will love you for descending this trail!
Trail runners rejoice, your knees will love you for descending this trail! James Dziezynski

Map of Lion's Lair

Preferred parking is at the start of the red trail. See directions below for details.
Preferred parking is at the start of the red trail. See directions below for details. James Dziezynski

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