4 Pass Loop, Maroon Snowmass Trailhead, Aspen - Snowmass, Colorado

4 Pass Loop - 26.8 miles

Maroon Snowmass Trailhead

Morning climb to Trail Rider Pass

Morning climb to Trail Rider Pass

Round-Trip Length: 26.8 miles (distances and gains may vary by route)
Start-End Elevation: 9,580' - 12,465' (max elevation on West Maroon Pass)
Elevation Change: +2,885' net elevation gain (+8,115' total elevation gain)
Skill Level: Strenuous
Dogs Allowed: Yes
Bikes Allowed: No
Horses Allowed: Yes
Related Trails:

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’).

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Interactive GPS Topo Map

Key GPS Coordinates - DATUM WGS84

  • N39 05.911 W106 56.452 — 0.0 miles : Maroon Lake - Maroon Snowmass Trailhead
  • N39 05.576 W106 57.373 — 1.0 miles : Rise up north side of West Maroon Creek
  • N39 05.327 W106 57.962 — 1.7 miles : W. Maroon Ck - Maroon Snowmass Trail split
  • N39 04.836 W106 58.283 — 2.5 miles : Campsite access on west end of Crater Lake
  • N39 03.916 W106 58.296 — 3.65 miles : Cross creek to east side of valley
  • N39 03.017 W106 58.787 — 5.0 miles : Steady climb through treeline
  • N39 02.156 W106 59.836 — 6.45 miles : West Maroon Pass (12,465')
  • N39 02.297 W107 00.526 — 7.25 miles : Split for Crested Butte - Frigid Air Pass
  • N39 03.137 W107 01.427 — 8.6 miles : Split for Hasley Basin - Frigid Air Pass
  • N39 03.214 W107 01.194 — 9.0 miles : Frigid Air Pass (12,409')
  • N39 03.380 W107 01.139 — 9.6 miles : Moderate in upper Fravert Basin
  • N39 04.049 W107 00.964 — 10.45 miles : Reach treeline
  • N39 04.891 W107 01.582 — 11.7 miles : Last campsite before waterfall descent
  • N39 04.775 W107 01.774 — 12.2 miles : Level in meadow below waterfall
  • N39 05.026 W107 02.520 — 12.9 miles : Cross creek
  • N39 05.314 W107 03.349 — 13.7 miles : Geneva Lake - Trail Rider Pass split
  • N39 05.619 W107 03.809 — 14.65 miles : Steep climb
  • N39 05.818 W107 03.747 — 14.8 miles : Geneva Lake - Trail Rider Pass split
  • N39 05.855 W107 03.303 — 15.4 miles : Level past tarn below Trail Rider Pass
  • N39 06.305 W107 02.942 — 16.25 miles : Trail Rider Pass (12,422')
  • N39 06.457 W107 02.700 — 17.0 miles : Winding descent to Snowmass Lake
  • N39 06.749 W107 02.095 — 17.8 miles : Patchy trees on rugged descent
  • N39 06.997 W107 01.705 — 18.35 miles : Snowmass Lake spur
  • N39 06.711 W107 01.219 — 19.15 miles : Short climb from lake basin
  • N39 06.533 W107 00.914 — 19.55 miles : Cross Creek
  • N39 06.584 W107 00.500 — 20.6 miles : Transition to high subalpine forest
  • N39 06.176 W106 59.683 — 21.8 miles : Winding ascent into alpine meadows
  • N39 06.109 W106 59.554 — 22.25 miles : Buckskin Pass (12,465')
  • N39 06.016 W106 59.098 — 23.05 miles Willow Lake Trail split
  • N39 05.614 W106 58.697 — 23.9 miles : Cross left over creek
  • N39 05.261 W106 58.423 — 24.6 miles : Steep descent through Minnehaha Gulch

Worth Noting

  • Overnight parking at Maroon Lake is limited and fills very quickly, especially on weekends. Get an early start to secure space and avoid additional foot travel or  having to take the shuttle.
  • Anticipate rapidly changing weather throughout the day, and manage time wisely to avoid passes and high, exposed areas when storms threaten. Plan travel accordingly, and have a backup plan if held up by weather.
  • Bear canisters may be required, especially late summer when bears are more active. Established campsites (e.g. around Crater Lake) are sometimes closed due to bear activity. Contact the Aspen Ranger District in advance for the latest information.
  • The 4 Pass Loop covers Aspen's most popular and heavily traveled corridors. Expect to see many people along the way, especially at passes and major trail junctions.

Camping and Backpacking Information

Backcountry Camping

  • Dispersed backcountry camping is permitted in the Maroon Bells - Snowmass Wilderness. Self-registration permits are available at each trailhead and/or Wilderness Boundary. Backpackers must carry a completed registration form with them for the duration of the trip.

  • There is no fee for this permit, however there's a $10 fee to access the Maroon Lake - Maroon Snowmass Trailhead by car.
  • Bear Canisters are now required for overnight backcountry stays in the Maroon Bells - Snowmass Wilderness.
  • Camping is prohibited within 100' of any trail, lake or stream. Group size is limited to 10 individuals (or 15 with people + stock).
  • Camping is not permitted in the alpine meadows below West Maroon Pass and Buckskin Pass (either side). Use designated sites located at and below treeline.
  • Campfires are not permitted at Crater Lake and Snowmass Lake.
  • Campfires are otherwise permitted in the Maroon Bells - Snowmass Wilderness, with potential seasonal restrictions. Campfires are not permitted above or within .25 miles (440 yards) of treeline, or within 100' of any trail, lake or stream. Additional location-specific restrictions may also apply.
  • Contact the Aspen Ranger District (970.925.3445) for the latest weather, trail conditions and trail-specific guidelines when planning your trip.

Fishing Information

  • Fishing is permitted at Maroon Lake, Crater Lake, Snowmass Lake and along all related streams with a valid Colorado fishing license.

Rules and Regulations

  • Dogs must be leashed at all times in the Maroon Bells - Snowmass Wilderness.
  • Due to heavy use, campfires are not permitted at Crater Lake and Snowmass Lake.

Directions to Trailhead

The Maroon Lake - Maroon Snowmass Trailhead is located 9.2 miles west of Highway 82 on Maroon Creek Road. The designated overnight parking lot is located 8.9 miles from the turnoff, just before the day-use parking area.

From Highway 82 in Aspen, follow the roundabout 1 mile NW of town onto Maroon Creek Road. Follow Maroon Creek Road to all designated parking lots. Call 970.925.3445 with specific questions about seasonal road access and shuttle schedules:

  • There's a $10 fee to access the Maroon Lake - Maroon Snowmass Trailhead by car. The Welcome Station is located 4.7 miles up Maroon Creek Road. Use the self-pay station just past the Welcome Station if no attendant is on duty.
  • Access by car is limited in the summer from 7am - 9am, and 5pm - 7pm. Visitors from 9am - 5pm must park at Aspen Highlands Village Parking Lot and take the Shuttle Bus to the trailhead. This parking area is located 1.4 miles up Maroon Creek Road and is well-marked.
  • Road access restrictions do not apply to overnight backpackers. Backpackers must pay the fee, but can proceed to the overnight parking lot and bypass the shuttle.
  • There's a $6 fee to take the shuttle from Aspen Highlands Village ($3 on select weekdays). The shuttle operates everyday from mid-June to Labor Day.
  • After Labor Day, the road is open to all cars Mon-Thurs; restrictions only apply Friday-Sunday. The shuttle runs Friday-Sunday as described above.
  • Cars with infants (children under 2) and handicap plates are exempt from road restrictions, year round. The $10 access fee still applies.

Contact Information

Maroon Bells - Snowmass Wilderness | Aspen Ranger District
806 West Hallam
Aspen, CO 81611
970.925.3445

Maroon Bells - Snowmass Wilderness | Sopris Ranger District
620 Main Street
Carbondale, CO 81623
970.963.2266

White River National Forest
900 Grand Ave.
P.O. Box 948
Glenwood Springs CO 81602
970.945.2521 | 970.319.2670

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