Aspen, CO: Four Pass Loop
Backpacker editors just named the Four Pass Loop one of our favorite trips ever—and Rockies readers agree, voting this their #1 hike. Here’s their advice for getting the 26-mile, four-day route’s sparkling creeks, peak-ringed lakes, and, yes, a quartet of 12,000-foot passes all to yourself.
Go counterclockwise, starting at Maroon Lake, where the purple-streaked Maroon Bells dominate the sky. Follow the north shore on the West Maroon Trail, then turn right at the signed junction. Switchback .2 mile to Crater Lake and a showstopping photo op of the Bells. Continue on West Maroon Trail 3.7 miles, then choose one of the established campsites edging the meadow. (Resist the urge to press on—the next campsite isn’t for five miles.)
On day two, continue uphill, gaining 800 feet in .9 mile as you inch toward 12,480-foot West Maroon Pass, perched between the Mars-like rock of Belleview Mountain and Mt. Bellview. The trail then descends into Hasley Basin, where you’ll hike past meadows of Indian paintbrush and columbine (peak flowers: late July) before turning right at a junction. Turn right again at a three-way junction and gain 400 feet to the crest of 12,415-foot Frigid Air Pass. From here, drop into lush Fravert Basin before reentering a conifer forest. Continue west for 1.3 miles to your second campsite, one of several spots scattered among ponderosas 150 feet from the North Fork of the Crystal River.
Next morning, you’ll ford the 20-foot-wide creek. At mile 13.7, turn right and switchback steeply through aspen groves en route to pass #3: 12,400-foot Trail Rider Pass, just below Snowmass Peak. Drop to Snowmass Lake, your next camp. On your final day, turn right at the junction and hike beneath sheer, red-rock cliffs and across Snowmass Creek before powering up to 12,462-foot Buckskin Pass. Look for mountain goats at mile 21.5; you can often spot nannies with kids in summer. Rejoin the West Maroon Trail to finish the loop.
Maps: USGS Maroon Bells and Snowmass Mountain ($8, store.usgs.gov)
Permit: Register at trailhead; (970) 925-3445
Gear up: Ute Mountaineer, 308 S. Mill St., Aspen, CO; (970) 925-2849
-Mapped by Kristy Holland
Trail Facts
- Distance: 41.9
Waypoints
FPL001
Location: 39.099651, -106.937668
The trailhead parking lot is equipped with toilets and drinking fountains. Though there are three lots, they may fill on peak weekends and even overnight visitors might have to take the shuttle bus from the Aspen Highlands Village at the base of Maroon Creek Road.
FPL002
Location: 39.098534, -106.940826
Follow Crater Lake Trail signs through the parking area and along the north shore of Maroon Lake. Be sure to stop for photos at this picturesque spot.
FPL003
Location: 39.098091, -106.94603
Turn right at the signed Y-junction, and head uphill toward Crater Lake.
FPL004
Location: 39.097122, -106.947838
The trail crosses two plank bridges just before a self-registration kiosk at the wilderness area boundary. Overnight hikers are required to fill out the free registration tag and leave detailed plans.
FPL005
Location: 39.091442, -106.958328
The trail opens up after a few short switchbacks and begins a level, 0.3-mile wind through lichen-covered piles of angular rock. Up ahead you'll catch a glimpse of Crater Lake's muddy waters on the left.
FPL006
Location: 39.088654, -106.965958
Turn left at this trail junction to follow the West Maroon Trail #1970. If you had a late start from the trailhead, you may choose to stop for the night at one of several Crater Lake campsites (site 6 is a favorite). If you're prepared for a longer hike, continue left up the valley toward West Maroon Pass.
FPL007
Location: 39.08429, -106.969894
A split-log bridge precedes this ponderosa-shaded clearing. Pass left-hand spur trails to Crater Lake's Campsites 7-9 and 10-11 up ahead.
FPL008
Location: 39.078888, -106.971786
The trail winds atop a rockfall and scree field. Northern views of Crater Lake are a little distracting, but the well-trod trail is easy to follow.
FPL009
Location: 39.065048, -106.971903
Water levels may be low in late summer, but this first substantial river crossing at mile 3.5 might be a snowmelt-swollen challenge in early summer. On the river's east side, a rocky clearing is a good spot to stop and have a snack and wring out your socks.
FPL010
Location: 39.055191, -106.976898
Several user-created trails merge on the opposite side of this 10-foot stream crossing. In late summer you may be able to stay dry, but expect to get wet when the river is swollen in early spring.
FPL011
Location: 39.042486, -106.986365
There are no designated campsites above Crater Lake, but camping is allowed. Use established sites (there are 2-3 sites around the edges of this meadow) to reduce impact along this heavily-used trail.
FPL012
Location: 39.036419, -106.997261
After rolling uphill and across some easy stream crossings, the climb intensifies as the vegetation and air thins near the pass. Alpine meadows and flowers give way to red-tinted rocks for the final few hundred feet of climbing.
FPL013
Location: 39.035732, -106.997307
West Maroon Pass, a 12,480-foot shoulder between Mount Bellview to the south and Belleview Mountain to the north, offers spectacular views of the valleys on either side.
FPL014
Location: 39.038279, -107.008702
Turn right at this signed Y-junction toward Frigid Air Pass. The trail climbs gently to the northwest.
FPL015
Location: 39.042725, -107.010805
There are no adequate campsites on this steep, hillside. Plan to spend your first night on the east side of West Maroon Pass, or allow plenty of time for a very long day one (over Frigid Air into Fravert Basin).
FPL016
Location: 39.052194, -107.023779
Hang a right at the signed 3-way junction. You'll traverse a grassy bowl beneath Frigid Air Pass before turning sharply uphill.
FPL017
Location: 39.053846, -107.020398
This short, but very steep and loose 400 foot climb ends at the 12,415-foot pass. Welcome views of the Fravert Basin's grassy expanse and the Maroon Bells' rugged backsides await.
FPL018
Location: 39.06726, -107.016007
The trail drops through shrubby alpine meadows and enters the woods for the first time in 5 miles. As the trail enters the woods it passes a few small, slanted campsites.
FPL019
Location: 39.077617, -107.019029
The trail crosses several drainages as it winds down the basin's upper half.
FPL020
Location: 39.081462, -107.025587
This shady campsite is large enough for several tents, but within a few hundred yards along the trail there are other, smaller sites as well.
FPL021
Location: 39.081344, -107.027962
This ledge offers spectacular views into the basin's lower half. You'll catch glimpses of a waterfall on your right before the trail turns sharply downhill over several switchbacks.
FPL022
Location: 39.082489, -107.041329
A Halsey Basin trail and westbound user trails merge at an unmarked junction in a clearing near a large, fallen tree. Continue straight toward the next junction before turning right, or turn right here to follow the faint user-trail toward the river.
FPL023
Location: 39.082607, -107.042244
This shaded campsite sits near a creek and is less than 150 yards away from the North Fork Crystal River crossing.
FPL024
Location: 39.083748, -107.041975
The trail's most substantial river crossing is a wet 20-foot wade across the North Fork Crystal River at mile 11. Consider bringing trekking poles for this section of the trip.
FPL025
Location: 39.088512, -107.05574
Turn right at the Y-junction toward Trailrider Pass. The next 1.5 miles zigzag up a steep, aspen-dotted hillside.
FPL026
Location: 39.096933, -107.062464
Turn right at this Y-junction and continue following signs north and east toward Trail Rider Pass. Another set of trails leads west toward Geneva Lake.
FPL027
Location: 39.098566, -107.052218
There is a small lake, a few lumpy campsites, and a small stream in this alpine valley below Trail Rider Pass.
FPL028
Location: 39.105086, -107.04904
A few short, steep switchbacks top out at 12,400-foot Trail Rider Pass. Snowmass Peak looms to the north and the trail shoots left and switchbacks downhill toward Snowmass Lake.
FPL029
Location: 39.113211, -107.034163
On a steep hillside just above Snowmass Lake, the trail winds around and across several scree fields. You'll have to rock hop on a few short sections of trail.
FPL030
Location: 39.116675, -107.02836
Continue straight at this 3-way junction to head toward Buckskin Pass. Optional: turn left for a 10-minute detour to an open picnic-worthy clearing near the lakeshore.
FPL031
Location: 39.117432, -107.030106
This clearing offers great views of Snowmass Mountain looming above the lake's western shore. There are several campsites in the forest just east of here.
FPL032
Location: 39.117172, -107.02636
Go straight at 3-way junction to continue toward Buckskin Pass. Or, turn left to scope out several individual campsites and a larger group site, too.
FPL033
Location: 39.108967, -107.016304
This rocky outcropping hides another campsite, just 100 feet to the left of the trail. Sites like this one, away from the lake, are likely to be less crowded during peak summer weekends.
FPL034
Location: 39.107479, -107.008934
After passing beneath a red-hued rock face, the trail traverses a meadow over a series of steep, loose, rocky switchbacks.
FPL035
Location: 39.105953, -107.004135
The trail crisscrosses Snowmass Creek near the east side of this marshy wetland area. The trail turns uphill for its final pass-bound climb.
FPL036
Location: 39.102016, -106.992546
At mile 21.5 the trail hits 12,462-foot Buskskin Pass before turning downhill toward the trailhead (the route's high point). Snowmass Mountain dominates the western view and grassy slopes nearby offer dramatic contrast. Watch for mountain goats that frequent the rocky outcroppings above the pass.
FPL037
Location: 39.100254, -106.98497
Stay straight at the 3-way junction continuing downhill and bypassing the Willow Pass and Willow Lake Trail.
FPL038
Location: 39.093544, -106.9786
A shallow 20-foot stream crossing here may present trouble when water levels are high, but a wide section of relatively flat, pine-covered trail crosses several small streams up ahead.
FPL039
Location: 39.090641, -106.977905
Stop at this rocky outcropping for a peek into Minnehaha Gulch. Be careful near the cliff edge, the log-jammed river is about 100 feet below the rocky cliff.
FPL040
Location: 39.08902, -106.969559
A stretch of broken aspen is evidence of this area's winter avalanche danger.
FPL041
Location: 39.088654, -106.965958
Continue straight at this 3-way junction to close this route's 23-mile loop. It's an easy, rolling 1.7 miles downhill toward the trailhead.
Below Trail Rider
Location: 39.100218, -107.049714
The valley and alpine lake on the west side of Trail Rider Pass.
Aspens
Location: 39.090359, -107.057535
The hillside path toward Trailrider Pass switchbacks through small groves of aspen.
Basin Views
Location: 39.081207, -107.0278
A northwest view of the North Fork Crystal River's basin near mile 11.6.
Cascade
Location: 39.099027, -106.984563
If you need a mid-downhill rest, stop at this trail-side cascade. It's just below treeline and has a few flat-topped rocks perfect for sitting on.
Fravert Basin
Location: 39.083472, -107.041699
Looking back toward Fravert Basin at a riverside junction just before the North Fork Crystal River crossing.
Fravert Basin
Location: 39.053785, -107.020097
A view of the Fravert Basin from Frigid Air Pass.
frigidair.jpeg
Location: 39.052118, -107.023959
Frigid Air Pass is just a short, steep climb above this trail sign at mile 8.5.
Maroon Bells
Location: 39.098228, -106.942077
A view of the Maroon Bells from the trailhead.
Pass Climb
Location: 39.036853, -106.997309
A hiker climbs the rocky, open trail toward West Maroon Pass.
Trail Rider Pass
Location: 39.105022, -107.048936
The view of Snowmass Lake from Trail Rider Pass.
Stream Crossing
Location: 39.065115, -106.971302
Even though this late-summer stream crossing is dry and easy, use caution on slick rocks.
Wildflowers
Location: 39.045119, -106.985421
Summer wildflowers decorate already spectacular views of the 13,000-foot bowl above West Maroon Creek.
Trail 1970
Location: 39.088502, -106.966109
West Maroon Trail #1970 turns south toward Crater Lake.
Trailhead Bus Stop
Location: 39.098494, -106.940274
A shuttle service stops at the trailhead and maybe the access only option for peak-season hikers.
Trail Rider View
Location: 39.104955, -107.048979
The southwestern view from Trail Rider Pass.
West Maroon Pass
Location: 39.042453, -106.986108
A picturesque campsite below West Maroon Pass.
