Mount Sanitas: 3 Routes to an Iconic Boulder Peak
- Stephen Warner
- Dec 26, 2023
- 4 min read
Updated: Apr 3
Located right outside Boulder, Mount Sanitas has everything you could want in a convenient hike. It’s a little challenging, has great views, and if you’re lucky—some wildlife (but definitely a dog or twenty). With three distinct routes to the summit, it’s the kind of hike you can do again and again without it getting old.
Trail Info
Trailhead Name | Lion's Lair / Sanitas Ridge/ Sanitas Valley + East Ridge |
Distance to summit (one way) | Lion's Lair: 2 miles / 3.6 km Sanitas Ridge: 1.3 miles / 2.1 km Sanitas Valley/East Ridge: 1.9 miles / 3.1 km |
Estimated time | 2-3 hours (all routes) |
Elevation gain | Lion's Lair: 800 feet / 244 m Sanitas Ridge: 1,250 feet / 380 m Sanitas Valley/East Ridge: 1,250 feet / 380 m |
Highest point | 6,821 ft / 2,079 m (Mount Sanitas) |
Permits / fees | None |
Parking | Lion's Lair: Pull-off along the highway Sanitas Ridge, Valley: Paved lot |
Toilets? | Lion's Lair: None Sanitas Ridge, Valley: Pit toilet at parking lot |
Dog friendly? | Lion's Lair: No (prohibited) Sanitas Ridge, Valley: Yes |
Know before you go
This is a very popular hike. Both Mount Sanitas and the nearby Flatirons get tons of foot traffic, especially because they’re so close to Boulder. Try going midweek or early in the morning to avoid the crowds.
Parking lots can fill up fast, especially on weekends. Arrive early or be ready to scout for street parking. Just be mindful of posted signs if you're parking in a neighborhood.
The trail is open year-round, but winter conditions can bring snow and ice. Check the forecast and trail reports, and consider tossing microspikes in your pack if you're hiking during colder months.
Which route should I choose?
Beyond distance, gain, and dog policy, here are a few other things to consider:
Sanitas Ridge to Valley Loop is the classic route. It lets you do the steeper section uphill and take a more mellow trail back down.
Lion’s Lair is the gentlest option. It’s a peaceful, forested trail with consistent switchbacks and smoother footing. There's less gain and no scrambling.
Sanitas Valley + East Ridge has extra access points if you’re looking to shorten your hike. You'll park in residential areas, so watch for signage and restrictions.
Sanitas Ridge
After (hopefully) scoring a spot in the Centennial Lot, you’ll cross the highway and hit your first junction. This is where you decide whether to head up Sanitas Ridge or Sanitas Valley.
Sanitas Ridge starts with some big “stairs” that’ll get your heart rate up fast.
There are plenty of lookout spots along the way—great places to catch your breath and soak in the views. That trail you’re seeing in the distance? That’s Sanitas Valley Trail.
One of the best parts of this route is how open it is. You’ll get sweeping views almost the entire way. Turn around and you’ll see the Flatirons, home to some of Boulder’s most famous hikes and climbs.
Look the other direction and you’ll spot the (often) snowcapped Front Range. On a clear day, you can see peaks that top 12,000 and even 13,000 feet.
The final push to the summit is short but steep. Views waiting at the top.
Sanitas Valley / East Ridge
If instead you turned right at that first junction, you’d find yourself on the Sanitas Valley Trail. It starts off flat and open. It is also super popular—you may see more dogs than people.
Eventually, you’ll hit some switchbacks and start gaining elevation. This is where the trail becomes East Ridge. From here, the grade feels similar to Sanitas Ridge.
Golden eagle sighting! Its wingspan was huge when it finally stretched out and glided away from its perch.
The East Ridge climb (or descent) has some steeper parts with rough footing. You might need your hands in places. I definitely wouldn’t want to be on this section if it were wet or icy.
Lion's Lair
Now for option #3: Lion’s Lair Spur. This one starts from a completely different area than the previous two. There’s no designated lot. You’ll park in a pull-off along the highway.
Important note: Lion’s Lair Spur Trail and Lion’s Lair Trail are different. They start at different points along the road. I started on the Spur, which is the shortest way to the summit and begins farther up the hill. Eventually, both trails merge, so either way, just follow the switchbacks heading uphill from the junction above.
This trail has a totally different feel than the other options with a dirt path, forested, mellow grade. Less hustle, more chill.
Still, there are some killer views of the Front Range peeking through the trees. Honestly, you can’t go wrong with any of the three routes.
The Summit
No matter which way you go up, the reward is the same—panoramic views from the top of Mount Sanitas. From here, you can look out over all of Boulder and, on a clear day, spot the Denver skyline shimmering in the distance.
It’s easy to see why this place gets so much love. A convenient, beautiful little mountain like this is exactly why I’m so happy I moved to this state.
SS Reflections
I love hikes that feel like a “choose your own adventure. ”Mount Sanitas checks that box perfectly. It’s not alpine, it’s not remote, and yeah, you won’t be alone up there. But when it’s this close, this scenic, and this flexible, it’s hard not to love it.
Other Helpful Resources
This Boulder County website which will reports the status of these trails
