The Four Pass Loop is one of the top hikes in Aspen and a quintessential Colorado backpacking trip, traversing high alpine passes, wildflower-filled valleys and dark blue lakes, more than 26 miles and more than 7,000 feet. It tests the soul, and feeds it at the same time. The loop circumnavigates the iconic Maroon Bells peaks and crosses four passes: West Maroon (12,500 ft.), Frigid Air (12,415 ft.), Trail Rider (12,420 ft.), Buckskin (12,500 ft.). It’s typically a three- to four-day backpacking trip done clockwise, but can be done in the opposite direction. Ambitious trailrunners also tackle the loop in one day.
The trailhead starts at Maroon Lake and the entrance to the Maroon Bells-Snowmass Wilderness Area. Overnight parking at the trailhead is extremely limited, so it’s recommended to park at Maroon Bells Basecamp and take a paid shuttle ($8/adults, $6/children) directly to the Maroon Bells-Snowmass Wilderness Area.
Parking at the trailhead is prohibited between 8am and 5pm from mid-June through October 1st, but if you happen to park before then you can pay between $5 and $10 to park overnight.
The hike starts at 9,580-feet at the Maroon Lake trailhead. The first 1.8 miles to Crater Lake climbs through giant aspen groves. Because this part of the wilderness area provides access points to many of the surrounding 14ers and different trails, like Buckskin Pass, it can be very crowded.
Once past Crater Lake, however, crowds dissipate and the long yet moderate climb up West Maroon Creek is stunning. The trail meanders along the creek before popping into high alpine tundra above the tree-line. West Maroon Pass is known for some of the most breathtaking and colorful wildflowers in the area, especially from mid-July into August. There are some campsites in this area. The last mile to the first pass is a set of steep switchbacks, but the view at the top is the reward.
From here, its descends quickly and in 1 mile, the trail intersects with Frigid Air Pass. Take a right (other hikers will continue to Crested Butte by staying on the main trail). It ascends for about 1 mile and Frigid Air can be seen high above, reached by a series of steep switchbacks.
From the second pass, Frigid Air, Fravert Basin can be seen below. The trail descends through an alpine field and enters a spruce forest heading toward the North Fork of the Crystal River. Along the river, there are several campsites; remember to camp at least 100 feet from the stream. After another 1.5 miles, the trail begins a series of steep switchbacks adjacent to the stream—also a stunning waterfall with high water.
In another mile, the trail branches just after a small clearing. Here the trail turns right. When it forks, take the right for .75 of a mile, and then it forks again. Take the right fork toward Trail Rider Pass. Of course, the trail goes back up here! Continue on the trail, noting where it veers off to the left for Geneva Lake. Hike up and up until the third pass is reached, Trail Rider. From here, Snowmass Lake is visible.
Here a breaktaking descent delivers hikers to Snowmass Lake. Opt to camp at the many sites here, or continue on the loop by getting on the Maroon-Snowmass Trail and heading toward Buckskin Pass. After crossing Snowmass Creek, the trail ascends to the last pass, Buckskin. There is some camping about half way up here, and keep in mind there is nothing until the other side for Buckskin Pass in the Minnehaha Gulch area. Reach the top of Buckskin Pass for the last views about 12,000 feet, where the Maroon Bells share the ridge and Pyramid Peak can be seen across the valley. And then, as they say, it’s all downhill from here.
ThunderstormsPlan hikes early in the day to avoid afternoon thunderstorms.
Leave No TraceDon’t leave anything behind. This is a fragile high alpine ecosystem and is already suffering because of overuse. Pack out all trash, bury human waste 6-8 inches deep and at least 100 feet away from the trail.
DogsDogs are permitted but must be leashed. This is a strenuous hike and should be attempted by people with backpacking experience. As for dog poop? Carry it out, please.
BearsBear activity is common in this area. It’s required to carry a certified bear-proof container and place all food, drinks and cooking utensils in it at night.
Stream CrossingsStream crossings can be dangerous during runoff periods. Consider bringing waterproof shoes to cross the streams and make sure to unbuckle your pack.
Prepare for All SeasonsRemember to pack appropriately and be prepared for all conditions and events.
Note: This is not an official trip guide. Please visit the US Forest Service website or office for thorough trail descriptions, and remember to pack a map and directional tools as well.