Memorial Day Sale! Get a year of AllTrails Pro for only $14.99
Get Started

Best trails in Boulder Open Space

27634 Reviews
Looking for a great trail in Boulder Open Space, Colorado? AllTrails has 113 great hiking trails, running trails, mountain biking trails and more, with hand-curated trail maps and driving directions as well as detailed reviews and photos from hikers, campers, and nature lovers like you. Ready for some activity? There are 47 moderate trails in Boulder Open Space ranging from 0.9 to 13.2 miles and from 5,072 to 8,464 feet above sea level. Start checking them out and you'll be out on the trail in no time!
Show more
Map of trails in Boulder Open Space
Park information
Helpful links
Top trails (113)
#1 - Royal Arch Trail
Boulder Open Space
hardYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(4180)
Length: 4 mi • Est. 2 h 37 m
Start on Chautauqua Trail by the ranger station. After crossing a grassy meadow, you enter a pine forest. Start paying attention to signs for Royal Arch as a number of other trails branch off. You knoShow more
#2 - Mount Sanitas and Sanitas Valley Loop Trail
Boulder Open Space
hardYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(2078)
Length: 3.2 mi • Est. 2 h 8 m
While parts of this hike are dog friendly, dogs are not allowed on the Lions Lair section of the trail. A wonderful "desert like" hike with great rock formations, vistas of Boulder CO, and rock scrambShow more
#3 - First and Second Flatirons Loop
Boulder Open Space
hardYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(1198)
Length: 2.5 mi • Est. 1 h 59 m
The flatirons are striking, tilted, sandstone rock slabs that form Boulder's beautiful backdrop. There are five distinct flatirons on the western side of Boulder. The route on this page takes you to tShow more
#4 - Bear Peak via the Shadow Canyon Trail
Boulder Open Space
hardYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(823)
Length: 8.1 mi • Est. 4 h 17 m
The trail starts out very easy with well maintained walking trails. As you progress deeper and higher the terrain increases in difficulty; to the point of being slightly technical. The trail gets fairShow more
#5 - Chautauqua Trail
Boulder Open Space
easyYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(1397)
Length: 1.2 mi • Est. 46 m
This trail basically serves as the first "in-trail" that leads to many other popular hikes in the park such as the Flat Irons and Royal Arch. It is wide, well traveled, and slightly inclined, with vaShow more
#6 - Green Mountain West Trail
Boulder Open Space
moderateYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(1124)
Length: 4 mi • Est. 1 h 38 m
Please note: The Sacred Cliffs at 7,978 feet are closed until August 1st due to nesting raptors.Show more
#7 - Mallory Cave
Boulder Open Space
moderateYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(862)
Length: 2.4 mi • Est. 1 h 31 m
NOTE: The cave itself is permanently CLOSED. There are SEASONAL buffer zone closures including many rock climbing routes from April 1 to October 1 for roosting bats. The permanent closure of the cShow more
#8 - Gregory Canyon, Range View and Flagstaff Trail Loop
Boulder Open Space
moderateYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(816)
Length: 3.6 mi • Est. 2 h 16 m
This is a great moderately challenging loop with excellent views throughout. The trail is steep but generally well-shaded through the Flatirons. Most of it consists of single-track trail, except for aShow more
#9 - Lion's Lair Trail
Boulder Open Space
moderateYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(775)
Length: 4.4 mi • Est. 2 h 20 m
Lion's Lair Trail is a 4.4 mile heavily trafficked out and back trail located near Boulder, Colorado that features beautiful wild flowers and is rated as moderate. The trail is primarily used for hikiShow more
#10 - Bear Peak Canyon Loop Trail
Boulder Open Space
hardYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarYellow StarGray Star(519)
Length: 7.6 mi • Est. 4 h 58 m
Along a lonely canyon to a ridge leading to a peak. This hike starts at the NCAR parking lot. Head west to the Mesa trail then south. At the Bear Peak canyon trail junction head west. This canyon takShow more
Showing results 1 - 10 of 113