Skyline Traverse: A Full Day Hiking the 5 Highest Peaks Around Boulder, CO
Boulder’s backdrop of jutting rock slabs not only makes for a compelling skyline, but provides the terrain for an epic day hike close to the city. South Boulder Peak, Bear Peak, Green Mountain, Flagstaff Mountain, and Mt. Sanitas—the five highest peaks surrounding the city—make up the Skyline Traverse. With about 6,000 feet of elevation gain over 20 or so miles, hikers are in for an enchanting day of diverse ecosystems with spectacular views both of the city to the east and the mountains to the west.
Ranges from 16-26 miles, depending on which trails you choose and whether you hike point-to-point or create a loop. For a point-to-point hike (between 16-20 miles), start either at South Mesa Trailhead to the south or Mt. Sanitas Trailhead to the north. For a loop hike, which will be closer to 24-26 miles, a more central starting point would be Chautauqua Park or the National Center for Atmospheric Research (NCAR).
Located in the iconic Rocky Mountain Flatirons, this hike hits the five highest peaks in the foothills surrounding Boulder, CO. Due to its proximity to an urban setting, this hike can start and finish in several different locations, depending on your logistics and the level of challenge you’re seeking.
Terrain and Scenery
The hike is moderate to difficult. There’s a system of well-maintained, connected trails throughout the area. With a total elevation gain of about 6,000 feet, this hike makes for a solid day. However, if you’re heading south to north, once you climb the initial 3,000 feet to your first peak (South Boulder Peak), you’re mainly hiking rolling terrain along the ridgeline until you drop back down to Boulder before ascending your final peak of the day (Mt. Sanitas).
Hikers will see a mosaic of ecosystems, from grassland to pine forests to rocky outcroppings and mountain streams. The Traverse also showcases views to the east overlooking Boulder, Denver, and the plains beyond.
Straightforward. Check out a trail map of the area in advance and know your turnoffs. The trails are not particularly well marked, but if you’ve looked at a trail map in advance or are carrying one with you (recommended), you should have no problem. The city of Boulder owns and maintains these trails, and they provide a good interactive map of the trails on Open Space and Mountain Parks land, found here. You can print a map of the area and highlight your route, or plot it on a mapping app.
From south to north, you’ll look for Shadow Canyon, Bear Peak West Ridge Trail, Green Bear Trail, Green Mountain West Ridge Trail, Ranger Trail, Flagstaff Trail, View Point Trail, Lion’s Lair Trail, and Sunshine Canyon Trail.
Depending on which direction you hike and whether you want to make it a loop, there are many options for where to park, including South Mesa Trailhead, NCAR, Shanahan Trailhead, Chautauqua Park, or Mt. Sanitas Trailhead. For a point to point hike, park at either South Mesa or Mt. Sanitas and get a shuttle to the other end (or bring a buddy with a second car). If you have non-Boulder County license plates, there’s a $5 fee to park at South Mesa.
For my south-to-north hike, I parked at Mt. Sanitas Trailhead and rode with a friend to South Mesa Trailhead. I chose south to north to get the biggest climb of the day behind me early. It’s about a 3,000-foot climb up Shadow Canyon to South Boulder Peak. From there I crossed the saddle over to Bear Peak, and descended via the Bear Peak West Ridge Trail. At the fork, I turned left on Green Bear Trail and hiked about 1.5 miles to the Green Mountain West Ridge Trail. I took that to Green’s Summit, then backtracked to Ranger Trail, which descends about a mile until it forks left toward Flagstaff Road. Once over the underwhelming Flagstaff summit, I found Flagstaff Trail, which I followed down to View Point Trail, then down into Eben G. Fine Park. After crossing Boulder Creek, I made my way toward Sanitas via Sunshine Canyon, hit the summit, and returned to my car via the East Ridge Trail.
Why Hike This Trail
If you live in the area, this is a classic hike. The Boulder County Open Space and Mountain Parks are arguably some of the best in the country. Planning this hike is simple enough to be done in an afternoon and the logistics are easy. The terrain is challenging enough to keep you engaged, but not overwhelmingly difficult. This trail allows you to put in a good day of miles and elevation gain, travel through the beautiful foothills ecosystems, and be rewarded with views of the city. Plus, you get to relax and refuel afterward in Boulder, with its many good restaurants and breweries.
Climate and Weather
This hike can be done year-round. Microspikes are recommended in the winter, as snow and ice often remain on the peaks, even when the ground is clear in town. Late spring and summer are beautiful times for wildflowers, and fall is a great time to spot golden aspens along the trail.
Beware of afternoon showers during the summer. Due to elevation changes, weather and temperatures can be quite different from your car to the peaks, so bring layers, and always have a wind or rain jacket. Don’t let your proximity to town cause you to be careless. It’s still a mountain environment with common threats like sudden thunderstorms and snowstorms, slippery rocks, sun exposure, and steep terrain.
Camping and Water Sources
While there is no overnight camping along this traverse, there’s a lot of national forest land near Boulder where you can camp before or after. A quick Google search will provide several options. In terms of water sources, there are a few creeks along the traverse where you could collect water if needed, but since it’s a day hike, it’s easy to carry the couple of liters you’ll need.
The length and elevation gain of the Boulder Skyline Traverse are ideal for a challenging day hike. Logistics are a breeze due to the accessibility of the trailheads and the proximity to town. The diverse ecosystems, the stunning views of Boulder, and the availability of post-hike libations make this hike a great activity for well-trained visitors and locals alike.
Much has been written about the Skyline Traverse, so you’ll have no trouble finding planning information. If you’d like to see an elevation profile or more photos (including the incredible inversion on the day I hiked), they’re posted here.
If you’re in the area, do a bit of planning, then get out there and hike this classic Boulder traverse. You won’t regret it!
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