Trail of the Week: The Skyline Traverse, Boulder, Colorado

This route lets you see almost everything that Boulder, Colo., has to offer for mountain running by traversing five of the tallest mountains in Boulder: South Boulder Peak (8,549 feet), Bear Peak (8,459 feet), Green Mountain (8,150 feet), Flagstaff Mountain (6,983 feet), and Mt. Sanitas (6,843 feet). Any one of those mountains can make for a great run, but combining all five in one loop can be downright epic.

There is a reason this is a frequent test piece for both pro and amateur ultrarunners. No matter how you combine the mountains—a variety of trailheads and interconnecting trails make numerous options possible—the Skyline Traverse is a long, arduous ultra-style run that has a variety of technical terrain and steep trails with a lot of gain and descent in relatively short distances. But it’s a great challenge with great views throughout—a perfect way to explore all that Boulder has to offer.

The most significant creek crossing in the first half of the route is at Bear Canyon, after descending from Bear Peak just before you head up Green Mountain. This is one of only a few places to fill up water mid-journey, if you need to. There is also a water fountain at the Chautauqua ranger station, and the ranger station atop Flagstaff Mountain usually has bottled water for hikers (because the fountain has been out of service in recent years.) The next (and last) place to get reliable water is the drinking fountain at Eben G. Fine Park.

From November to April, there is usually ice on the higher parts of the route, especially on north-facing trails. Some sort of traction is recommended for these sections.