4 Pass Loop - 26.8 Miles Round-Trip

The 4 Pass Loop runs 26.8 miles through the heart of the Elk Mountains and Maroon Bells-Snowmass Wilderness. This challenging trek scales four passes over 12,400' with stunning views and long stretches of open alpine travel.

Trail Map | Photo Gallery

• West Maroon Pass (12,465')
• Frigid Air Pass (12,405')
• Trail Rider Pass (12,415')
• Buckskin Pass (12,462')

Whether tackled as a trail run or a more leisurely 2-3 day trip, advance knowledge of the route will maximize time and ensure a safe and enjoyable outing.

While the distance is not overwhelming, steep climbs at high elevation with unpredictable weather are considerable factors. Carry a detailed map to track progress, anticipate passes and target campsites.

There are many designated sites along the way, with freedom to improvise under guidelines of the wilderness area (see details below). Contact the Aspen Ranger District (970.925.3445) for the latest conditions, closures, bear canister requirements and other useful tips before heading out.

The following description begins at Maroon Lake and travels clockwise on the loop:

1. MAROON LAKE - WEST MAROON PASS | 6.45 miles

9,580’ – 12,465’ @ Pass | 2885’ net gain | 3115’ total gain

The trail begins on the north side of Maroon Lake before rising away into thick aspens that break across an open rock field to the West Maroon Creek - Maroon Snowmass Trail split (1.7 miles : 10,110’). Bear left to begin clockwise travel on the loop.

The trail levels around Crater Lake to campsites on the far end. It bends S-SW above the inlet and undulates over rockslides at the base of Maroon Bells. It moves quickly up valley and crosses east over West Maroon Creek, where water can be swift during peak runoff (3.65 miles : 10,515’).

The trail rises steadily past treeline and crosses back to the west side through tall swaths of willow (4.5 miles : 10,905'). Travel steepens in short intervals through 5.45 (11,525’) miles into broad meadows below the pass. It climbs 940’ in the last mile on a ramp-like trail to West Maroon Pass (6.45 miles : 12,465’). The pass spans a small notch in the SW corner of the headwall, with great views down West Maroon Creek and the East Fork drainage on the Crested Butte side.

2. WEST MAROON PASS - FRIGID AIR PASS | 2.55 miles

12,465’ – 12,405’ @ Pass | 60’ net loss | 745’ total gain

This is the shortest pass-to-pass section of the loop, and arguably the easiest. The trail drops from West Maroon Pass to the split for Crested Butte and Frigid Air Pass (7.25 miles : 11,735’). It rises NW across high alpine meadows above the East Fork drainage, a notably airy stretch with great views over the popular thru-hike route to Crested Butte.

The trail splits right at a sign for Frigid Air Pass, and the unmarked left fork heads toward Hasley Basin (8.6 miles : 12,035’). Travel steepens on the last .15 miles up to Frigid Air Pass (9.0 miles : 12,405’).  Panoramic views include Maroon Bells and Fravert Basin, where you’ll spend the next 4.7 miles.

3. FRIGID AIR PASS - NORTH FORK CUTOFF TRAIL | 4.7 miles

12,405’ – 10,295’ | 2100’ net loss | 165’ total gain

The trail drops quickly from Frigid Air Pass into Fravert Basin, gradually moderating through expansive alpine meadows topped by red hued walls. It reaches treeline at 10.35 miles (11,425’), and edges close to North Fork Creek through brushy intervals with numerous designated campsites. This fast moving, nondescript section is ideal for making up time if not camping in the area.

It passes the last site at 11.7 miles (10,870’) before dropping steeply beside a waterfall into a wide, level meadow cut by oxbows of the North Fork (12.05 miles : 10,530’). It enters a cluttered forest before emerging in another meadow that funnels you east across the creek (12.9 miles : 12,440’).

The trail remains level above a kinetic section of creek to the Geneva Lake - North Fork Cutoff Trail split (13.7 miles : 10,295’). This is the lowest point of the loop (not counting the 1.7 mile leg from Maroon Lake to Crater Lake).

4. NORTH FORK CUTOFF TRAIL - TRAIL RIDER PASS | 2.55 miles

10,295’ – 12,415’ @ Pass | 2120’ net gain | 2210’ total gain

This strenuous section climbs above the North Fork through aspen groves and grassy slopes to a second split for Geneva Lake (14.8 miles : 11,390’). Note the trail gains 1095’ in just 1.1 miles to this junction.  The trail veers right and narrows into a steep gulch, then rises away on switchbacks that moderate across rolling alpine meadows below Trail Rider Pass.

The trail skirts a large pond (15.4 miles : 11,710’), the primary water source if camping in the area (small outlying ponds can dry out).  The reprieve ends with a 705’, .85 mile climb to Trail Rider Pass (16.25 miles : 12,415’). Views of the route leading up are exceptional, and even more so down the east side of Snowmass Lake.

5. TRAIL RIDER PASS - SNOWMASS LAKE | 2.1 miles

12,415’ – 10,980’ | 1435’ net loss | 55’ total gain

The trail drops steeply from Trail Rider on winding switchbacks with expanding views over Snowmass Lake and the formidable peaks above it: Snowmass Peak (13,619’), Hagerman Peak (13,841’) and Snowmass Mountain (14,092’).

It transitions quickly from alpine meadows to willow mats and treeline at 17.75 miles (11,510’). Conditions are rugged over washed out sections and talus leading to the Geneva Lake Trail – Maroon Snowmass Trail split (18.35 miles : 11,040’). Snowmass Lake is a short walk from here (18.37 miles : 10,980’).

6. SNOWMASS LAKE – BUCKSKIN PASS | 3.9 miles

10,980’ – 12,462’ @ Pass | 1482’ net gain | 1670’ total gain

The trail rises out of the Snowmass Lake basin into a thick forest, then drops to a wide opening along Snowmass Creek. The trail loses clarity leading to a bridge over the creek (19.55 miles : 10,860’); pay close attention on this braided approach.

Once over travel gradually steepens on long, methodical switchbacks to treeline, where views open across the Snowmass Creek drainage back to Snowmass Lake (20.05 miles : 11,575’).

Grades steepen on a winding course through high alpine meadows before relaxing on the final run to Buckskin Pass (22.25 miles : 12,465’). Buckskin Pass is the most spacious of the four, a long saddle with rangy views across the Elk Range and Snowmass Lake basin (north), and Maroon Bells and Pyramid Peak (south). Look for goats on adjacent slopes and ridges before making the final descent.

7. BUCKSKIN PASS – MAROON LAKE TRAILHEAD | 4.6 miles

12,462’ – 9,580’ | 2882’ net loss | 155’ total gain

The trail descends winding switchbacks through flower-carpeted slopes to the Willow Lake Trail split (23.9 miles : 11,745’). It narrows into Minnehaha Gulch and a stream crossing to the east side at 24.7 miles (11,030’).

It drops quickly through the gulch back to the Maroon Snowmass – West Maroon Creek Trail split (25.1 miles), where you began clockwise travel on the loop. Retrace your steps back to Maroon Lake on a variously rocky-rooted path to complete the 4 Pass Loop (26.8 miles : 9,580’).