Elevation: 7,807 ft
GPS: 39.952, -105.29 Google Map · Climbing Area Map
Page Views: 27,950 total · 46/month
Shared By: Josh Janes on Dec 31, 1969
Admins: Leo Paik, John McNamee, Frances Fierst, Monty, Monomaniac
43°F 6°C
Memorial Day
60°F - 35°F 16°C - 2°C
42°F - 32°F 6°C - 0°C
44°F - 34°F 7°C - 1°C
55°F - 39°F 13°C - 4°C
61°F - 42°F 16°C - 6°C
64°F - 43°F 18°C - 6°C
Access Issue: Temporary Trail and Raptor Closures Details


Devil's Thumb is the prominent spire that can be seen from just about anywhere in Boulder along the skyline of the Flatirons. It is just south of Bear Peak and is distinctly... thumb-shaped. Surely every climber in Boulder has had thoughts of climbing it at one point or another, and apparently earlier in the century, so did non-climbers: a steel ladder was put up at one time to make the summit easily accessible, but has long since been removed. A steel pole on the east side of the summit is all that remains of the ladder, but it serves as an excellent rappel point for those willing to brave a laborious approach to the Thumb. The western side of Devil's Thumb is an incredible, towering overhang, whereas the eastern side has its own, 20 foot overhang that makes the summit a technical climb no matter how you approach it. As far as routes go, there are two moderate routes up weaknesses on the east face, a 5.10d route up the southwest side, an aid route on the northwest side, and what looks like a very fun line of bolts on the north face.

Getting There

The best approach is from the South Mesa Trailhead. Take the Mesa trail west towards the Matron and Shadow Canyon. At the Mesa/Shadow Canyon junction, follow the Shadow Canyon trail NW up into the canyon. Pretty soon you catch glimpses of Devil's Thumb off to the east (right).

Once you begin to see a massive boulder/talus field on your right, break off at any time from the trail and rock-hop your way towards the spire: your goal is the northwest side of Devil's Thumb (at least for the moderate routes). The hopping gradually turns to steep hiking on loose rock, and the steep hiking on loose rock terminates in a few sections of class 4 scrambling - if you're unaccustomed to this it can be scary, but the sections are brief and you're very close to the base of Devil's Thumb at this point. Once you're there, hike around the northern side, and then up and over a boulder to gain access to the east face.

3 Total Climbs

Route Finder - Best Climbs for YOU!

Location: Devil's Thumb Change
Type:  to 
Sort by:   then:

Sun & Shade

Weather Averages

Days w Precip
Prime Climbing Season


A great way to approach the Devils Thumb is to climb the East Face of the Fatiron, which is the rock just north of the Maiden. From the summit, hike/scramble uphill to the right to the Thumb. An ascent of the Flying Flatiron would probably work, too.

Last I saw, those summit bolts were bogus - I hope no one raps off those. Do a belayed downclimb to the bar left over from the old ladder, and rap from there.

After an ascent of the Thumb, make sure you head into Boulder and the Walnut St Brewery for some fish 'n chips and a Devils Thumb Stout or two. Aug 13, 2001
The two bolts are on the south side of the East face about 10 feet from the summit. They had 3 or 4 weathered slings around them (10/6/01) which makes me think some folks are actually using them to rappel off of them on the East face side.

The bolts are very old and rusty, stick out about 1/4" and both hangers are, as you might expect, really loose. I used them as a belay set up to lower my partner down to the Iron bar for the standard rappel. The downclimb to the bar is not as easy as it sounds and could be disastrous for the second person downclimbing if he should slip...

I can see why some people may have opted for rappelling off of the manky bolts. Having said that, I'd rather downclimb. Them bolts are not to be trusted... and if they GO it's over...

Oct 8, 2001
Prior to 1982 or 1983 there was a refrigerator sized rock poised at the edge of the west overhang on the summit. That rock is no longer there due to two overzealous trundlers who happened to be on top one day. The two trundlers put their backs against one rock and pushed the refrigerator with their feet. Much to their amusement (dismay) the refrigerator actually slid off the top of the west face. There were a few seconds of silence and then everything changed. Shadow Canyon started exploding! As soon as the refrigerator hit ground zero, it started a chain reaction. The refrigerator sent car sized rocks in motion, which sent house sized boulders in motion, and so on. The trundlers made a hasty exit and headed back towards Denver. The huge dust cloud was still engulfing Shadow Canyon and could be seen from 92nd and Hwy 36 in Westminster! If anyone was coming up the east side of Shadow Canyon that day their pictures were on the side of a milk carton later that week. Boulder trundling is an age honored form of entertainment that climbers have enjoyed for hundreds of years. It is a national sport in Lithuania.The sport of trundling can be very dangerous and should not be practiced without first seeking professional instruction in proper technique with strict adherence to tradition. Back in 82 or 83 the two trundlers were lucky and no one was hurt. Does anyone else have a good trundling story that they could share? Aug 29, 2005
Mike Munger and I replaced the two, old, 1/4" Rawl buttonhead bolts as the anchor for this rock with 3/8" SS Rawl bolts and added quick links and chain for rappel.

This hardware for this work was provided by the American Safe Climbing Association (ASCA). They appreciate your support. Oct 7, 2005
Does anyone know a rough estimate of how long the approach is for this climb? And what the status is of the bolts on the top? Jun 3, 2008
Clint Locks
Clint Locks   Boulder
Ric-I made it to the base of the climb via Shadow Canyon in a little less than 2 hours. We descended to the east and hit the Mesa trail. It was indeed a bushwack in places, but not that bad. If one AScended that way, it could be tricky to find the base of the climb, as the forest is pretty thick toward the top.

From the chain anchors on top, a 60 mtr rapel comes up a little short. It will, however, deposit you on a small ledge from which you can easily down-climb the ~12 remaining feet to the ground. Also, if you choose to rap from the steel rod above the "Left Side" route instead, the down-climb to that is not a 'walk in the park'. ASCA: Thanks for the bolt! Oct 19, 2008
Tony B
Around Boulder, CO
Tony B   Around Boulder, CO
I went several times last summer and with a rope and light Rack, it was ~1:30 at a "tempo" pace. Which is to say that we were not slouching, but not racing. Oct 19, 2008
George Bell
Boulder, CO
George Bell   Boulder, CO
Thanks to Bruce and Mike for replacing the rappel bolts! From these bolts, one could do a mind-blowing free rappel to the west. I don't know how long a rope would be needed (rumor has it a 70m single-strand makes it). Also, you could probably not pull your ropes since the rappel is rigged to go east. But it would be a wild rap. Nov 17, 2008
Kyle Drott
Denver, CO
Kyle Drott   Denver, CO
I am glad to see as of 2008 that the rap bolts are in good order. I plan on doing this route very soon. Does anyone have a more recent report? It's been about ten years.... Oct 20, 2017
Mark E Dixon
Sprezzatura, Someday
Mark E Dixon   Sprezzatura, Someday
Rap bolts look great.

Approaching via the Apostle and the Flying Flatiron is super- minimal bushwhacking and fun scrambling. Aug 5, 2018