Boulder Skyline Traverse
The Skyline Traverse links the five summits on Boulder's western skyline in a single day, and it isn't an official trail: no agency publishes a distance or a gain for it, though hikers commonly report about 16 to 17 miles and roughly 5,900 feet of climbing point to point.
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Boulder Skyline Traverse quick facts
- What it is
- A link-up, not a trail. The Boulder Skyline Traverse strings together the five summits on Boulder's western skyline: Mount Sanitas, Flagstaff Mountain, Green Mountain, Bear Peak, and South Boulder Peak.
- Managing agency
- There isn't one for the route. The individual trails are City of Boulder Open Space and Mountain Parks. No agency publishes the traverse as a named route, so there is no official distance, gain, or difficulty rating for it.
- Distance
- Commonly reported at about 16 to 17 miles point to point. Reported figures vary with the trails you pick, and looping back to your car instead of shuttling pushes it to roughly 24 to 26 miles. Treat these as hikers' numbers, not agency numbers.
- Elevation gain
- Commonly reported at roughly 5,900 to 6,000 feet for the point-to-point version. Again, not an agency figure.
- Difficulty
- Very hard. Every one of the five summits is individually rated hard by OSMP, and this does all of them in a day.
- Time
- Widely reported at about 11 to 13 hours hiking. Runners go considerably faster; most people going for the first time should plan a full day and a headlamp.
- Dogs
- Rules change segment to segment and one popular link prohibits dogs entirely. Read the dogs section below before you bring one.
- Fee
- No fee for the trails. Parking is where it costs: Chautauqua and Gregory Canyon both charge, while Centennial and NCAR are free.
- Water
- None on route. There is no reliable water on the skyline. Carry everything, or plan a resupply where the route crosses a trailhead.
Why the numbers on this page are hedged
Everywhere else on this site we quote the managing agency and tell you which one. We can't here, and it's worth being upfront about why. The Skyline Traverse is not a trail. There's no sign for it, no agency maintains it as a route, and OSMP publishes nothing about it, because from OSMP's point of view you're just walking a series of its ordinary trails in a particular order.
So the distance and gain figures you'll see quoted, here and everywhere else, come from hikers rather than from a land manager, and they disagree with each other by a couple of miles and several hundred feet. That isn't sloppiness, it's the route genuinely varying with the trails you pick between summits. Use them to plan the shape of your day, not to calculate anything precisely.
The five summits
Each of these has its own guide with figures that are agency-sourced. If you want real numbers, they're on these pages, not on this one.
- Mount Sanitas: the northern bookend, straight up above downtown.
- Flagstaff Mountain: the low one, and the only summit with a road to the top.
- Green Mountain: the middle of the route, with a peak-finder marker at the top.
- Bear Peak: the rocky one, and the point where a long day starts feeling long.
- South Boulder Peak: the highest on the skyline, and the southern bookend.
Most people run the route north to south, finishing over Bear Peak and South Boulder Peak, though there's no rule about it and plenty go the other way.
Shuttle, or loop
This is the logistics decision that shapes everything else. Point to point is the shorter, cleaner version, at the commonly reported 16 to 17 miles, and it needs a car at each end or someone willing to collect you. Looping back to a single car is reported at roughly 24 to 26 miles, which is a materially different day and one that a lot of people underestimate. If you want the loop, starting centrally from Chautauqua Park or NCAR is the usual way to balance it.
Water, and the thing that actually goes wrong
There is no reliable water on the skyline. None. The route runs along dry, exposed ridges and south-facing slopes for most of its length, and the places it dips toward a trailhead are the only realistic chance to refill. Carry more than feels sensible, and if you're doing the loop version, plan a genuine resupply rather than hoping.
The second thing is timing. Boulder builds afternoon thunderstorms fast in summer, and this route keeps you on exposed high ground for hours. Starting before dawn isn't machismo, it's how you avoid being on Bear Peak at two in the afternoon watching a cell come over the Divide. Our thunderstorm safety guide covers the pattern, and the altitude guide is worth reading if you're new to town.
Dogs: read this before you bring one
The rules genuinely change underfoot. Parts of the route allow voice and sight control with a City of Boulder tag. Sections crossing NCAR federal property require a hand-held leash whatever tag your dog wears. And Lion's Lair, one of the common ways up or down Mount Sanitas, prohibits dogs outright. Plan the specific trails you'll use and check each one, rather than assuming a single rule covers the day.
Separately from the rules: 16 miles, 6,000 feet, no water, and hot rock is a lot to ask of a dog. Most shouldn't be on this one, however keen they look at the trailhead.
Fees and parking
The trails are free. Parking is where the cost lands, and it depends which end you start from. Chautauqua and Gregory Canyon both charge, while the Centennial Trailhead below Sanitas and the NCAR lot don't. If you're leaving a car overnight or before dawn, check the posted hours: Gregory Canyon closes at 9 p.m., earlier than most. See the OSMP parking permits guide.
Should you do it?
If you can comfortably do Bear Peak and Green Mountain on separate days and still feel good, you can probably do this with an early start and honest pacing. If either of those is currently a hard day on its own, the traverse will be a miserable one. There's no shame in doing it in two halves, and splitting at Chautauqua is the natural break.
Related trails and guides
- Best hard hikes near Boulder: the individual climbs, compared.
- Saddle Rock Trail: the steepest way onto this ground.
- Best trail running near Boulder: if you're moving faster.
- What to bring hiking in Boulder: the water question, in detail.
- Best views and summits: the payoff, one summit at a time.
Boulder Skyline Traverse FAQ
What is the Boulder Skyline Traverse?
It's an unofficial link-up of the five peaks on Boulder's western skyline: Mount Sanitas, Flagstaff Mountain, Green Mountain, Bear Peak, and South Boulder Peak. There's no trail called the Skyline Traverse and no agency maintains or signs it as a route. You're following a sequence of ordinary OSMP trails that people have agreed on.
How long is the Boulder Skyline Traverse?
No agency publishes a figure, because it isn't an official route. Hikers commonly report about 16 to 17 miles point to point with roughly 5,900 to 6,000 feet of elevation gain. If you loop back to your starting car instead of arranging a shuttle, the reported range climbs to about 24 to 26 miles. Which trails you choose between the summits changes the total, which is why the numbers you'll see quoted don't agree with each other.
How long does the Skyline Traverse take?
Commonly reported at around 11 to 13 hours of hiking for the point-to-point version. Trail runners do it much faster. If it's your first time, plan for a full day, start before dawn, and carry a headlamp for the end regardless of how confident you feel at the trailhead.
Can you bring a dog on the Skyline Traverse?
Think hard about it. Dog rules change from trail to trail across this route: some segments allow voice and sight control with a City of Boulder tag, sections on NCAR federal property require a hand-held leash regardless of any tag, and Lion's Lair, a common way up or down Mount Sanitas, prohibits dogs entirely. On top of the rules, it's a 16-plus-mile day with no water and hot rock. Most dogs shouldn't be doing this.
Do you need a shuttle for the Skyline Traverse?
For the point-to-point version, yes, or a very willing friend. Most people leave a car at each end or arrange a pickup. The alternative is looping back, which adds roughly eight to ten miles by the commonly reported figures. Starting centrally at Chautauqua Park or NCAR is the usual way to make a loop work.
When is the best time to do the Skyline Traverse?
Late spring through early fall, and start early. The summits are exposed and Boulder's afternoon thunderstorms build fast in summer, so the goal is to be off the high ground by early afternoon. Shoulder seasons work if the north-facing sections are clear of ice, and full winter turns it into a genuine mountaineering day rather than a long hike.
Sources
The five summits are documented by the City of Boulder. The route itself is not published by any agency, so its distance, gain and timing figures on this page are described as commonly reported rather than official.
Last checked . We verify trail facts against the managing agency, and we say so when a figure isn't published.