"The Boulder 20". Lying in the backyard of Boulder, Colorado, this peak challenge is a rite-of-passage for anyone in the Boulder area. Includes popular trailed peaks such as Green Mountain, Bear Mountain, and Mount Sanitas, but also less-visited peaks off the beaten path like Dinosaur Mountain and Shirttail Peak.
Highest peak
Thorodin Mountain
10,540 ft / 3,212 m
Most prominent peak
Thorodin Mountain
1,480 ft / 451 m prom
Most climbed peak
Bear Peak
132 climbs
Most difficult peak
Sugarloaf Mountain
Class 1
Difficulty breakdown
Class 1/2 1 peak
Class 3/4 1 peak
Highlights
Latest climbs
"First time I've run up to the top. The summit boulder is at the end of a dead-end trail, was maybe somewhat questionable whether going on it is "off-trail" but I only touched rocks so I'm gonna say I abided by the spirit of the law." — wazoheat • Sep 10, 2024
"8am start up the steep portion and looped it back down the valley trail. Earlier start would’ve helped avoid the heat but overall, a lovely day for a Boulder hike. Pretty views and great company. " — Katamount • May 28, 2024
"Quick leg up with Owen to check out Sacred Cliffs. Always a lovely view from the peak. Snow was manageable without traction but had to take it slow on some parts of the downhill." — benyboy • Jan 3, 2024
"1. Passed on the way up to Dinosaur Mountain. Didn't climb on the rocks past the fence.
2. Managed to tag this one! Sharp rock peak on the stratum west of dum (with the flat balanced rock). Super fun scramble/routefind up from Mallory Cave." — benyboy • Nov 10, 2023
"1. Passed on the way up to Dinosaur Mountain. Didn't climb on the rocks past the fence.
2. Managed to tag this one! Sharp rock peak on the stratum west of dum (with the flat balanced rock). Super fun scramble/routefind up from Mallory Cave." — benyboy • Nov 10, 2023