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Sunshine Lion's Lair Loop

 52 votes


5.3 Miles 8.5 Kilometers






1,302' 397 m


-1,321' -403 m



Avg Grade (5°)


Max Grade (18°)

6,802' 2,073 m


5,523' 1,684 m



Minor Issues 20 days ago
Snowy, Some Mud - some packed snow that's turned a bit icy on the first section along sunshine canyon. clearing up nicely from a few days ago. History

Getting forecast...

Great Mount Sanitas views are the reward for this gentler loop in Sunshine Canyon.

Megan W


Some parts of this loop are closed to dogs.
This enjoyable loop sees less traffic than the main attraction in this area, the Mount Sanitas Loop. The other advantages of this loop include a less arduous ascent on a shiny new trail and a quick, efficient descent.
Features: Views — Wildflowers — Wildlife
Dogs: No Dogs

Runner Notes

It's very smooth, runnable, non-rocky, and non-rooty on the Sunshine Canyon Trail, Lion's Lair Alternate, and Lion's Lair Trail ascent. It's steep, technical, and rocky on the Mount Sanitas Trail descent.


This loop combines several area trails into a varied, pleasant run. Starting from the Centennial Trailhead at the mouth of Sunshine Canyon, find the start of the Red Rocks Trail heading south from the toilets. Almost immediately, you'll leave the Red Rocks Trail and follow the Sunshine Canyon Trail as it branches off to the west and crosses a small ravine. Follow the nicely bench cut, contouring Sunshine Canyon Trail as it parallels the Sunshine Canyon Road. This section of low angle trail is not steep and has a mostly smooth surface, passing through fields and fir forest.

The Sunshine Canyon Trail ends at a residential driveway, adjacent to the Sunshine Canyon Road. To access the next part of the loop, carefully cross the road and head briefly up-valley until you reach the first dirt residential road on the right (east) side of the road. Run only a few feet up this road and look for a faint footpath just after the culvert on the uphill side. This is the beginning of the Lion's Lair Alternate Trail.

The Lion's Lair Alternate trail starts up a small ridgeline sparsely treed with fir. It is undergoing a re-route and partial re-build (as of spring 2015) so be aware that the start of the trail may be moved around a bit to include more switchbacks and prevent erosion. Switchback and contour up the western flank of Mount Sanitas, climbing gently past dry rocky outcrops. There are views of the continental divide and down into Sunshine Canyon. The trail is well constructed and features rock steps and good grading. The Lion's Lair Alternate trail eventually joins the Lion's Lair Trail at an early switchback.

Continue uphill on the recently built (completed in the fall of 2014) Lion's Lair Trail. Take gentle switchbacks through the ponderosa forest. The grade is never steep, and at least for now, the surface is impeccably smooth. The corners and water crossings show off just how well this trail was constructed. As you ascend, the views get better and better. Be sure to turn around and enjoy the high peaks in the distance. From the end of the trail, at the rocky summit of Mount Sanitas, all of Boulder is laid out in front of you.

Take a breather before descending the Mount Sanitas Trail. This is a steep, challenging descent down the spine and western edge of Mount Sanitas. Pass over rocky sections and numerous large step-downs. Expect a lot of hiker, runner, dog traffic on this section of trail. There are several rest spots where you can pull off to enjoy views of town and also the snowy peaks to the west. There are a few rutted steep sections with difficult footing. Towards the bottom, you'll pass some short cliffs popular with bouldering rock climbers. After one last series of tall wooden log steps, you'll cross an irrigation ditch and emerge into a small meadow. Keep to your right, crossing a stream and passing through a covered picnic pavillion. Carefully cross the Sunshine Canyon Road and head uphill to arrive back at the Centennial Trailhead parking area.

Flora & Fauna

A suprisingly wonderful variety of wildflowers in the sunny spots- especially in the early spring months (April & May).


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Your Check-Ins


Jan 20, 2018
Thomas Lindberg
First time running The Swoop. Runnable ascent in the clockwise direction (if I was fitter). Met the Boulder Running and Breakfast Club folks at top. 5.5mi — 1h 09m
Oct 29, 2017
Laura Hamman
Sep 21, 2017
sickest run 5.3mi
Sep 20, 2017
Becky Campbell
started up Sanitas
Aug 30, 2017
Brian O'Leary
Jul 16, 2017
Adam Ellis
Humbling. Hated the rocky downhill on Mt Sanitas trail. 5.4mi
Jul 9, 2017
WookieStick69 Thomas
amazing trail. nice and gradual. did not bring enough food and water. excellent training for a mountainous half marathon. 8.2mi
Jun 10, 2017

Trail Ratings

  4.6 from 52 votes


  4.6 from 52 votes
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801 Views Last Month
16,786 Since Apr 23, 2015
Intermediate Intermediate

Personally, I prefer going in the opposite direction on this loop. The steep climb a pretty good workout, and then you can stretch the legs back out during the descent. Great loop though. (Probably ran it at least a dozen times this year.) Dec 9, 2015
Todd Straka
Todd Straka   Boulder
One of my favorite loops from downtown. The plush trail on Lions Lair makes for a great run. Beware of that Sunshine trail in the winter though as it can get ice packed and super slippery across the slope as its north facing. Dec 11, 2015

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