The Four Pass Loop: 26 Miles of High Mountain Colorado Paradise

The renowned Four Pass Loop is perhaps the best-known hiking loop in all of North America. Located on the doorstep of Aspen, Colorado, and winding through both bustling, famous vistas and quiet, secluded ridges, this short trail offers a taste of some of the best Colorado has to offer — sparkling snow, bountiful wildflowers, alpine lakes, verdant forests, rushing streams, windy passes, and calm valleys all included. 

Four Pass Loop At a Glance

Photo: Troy Zohner

• Length: 26 miles, 8,000 feet of elevation gain
• Expected Completion Time: 3-4 days
• Location: West-Central Colorado
• Best seasons to hike: June – September
• Trail Type: Loop
• Scenery: Remote and rugged high Elk Mountains. Rich green forests, red-purple cliffs, bright blue alpine lakes, plentiful wildflowers (when in season). 
• Popularity: Heavy traffic
• Terrain: Difficult, the trail traverses (wait for it…) four high mountain passes with climbs of 1,500-3,000 vertical feet each.
• Navigation: FarOut is still standard for hikers here. If you’re a fan of paper maps, some assorted brands make high-quality, water-resistant products (like this and this).
• Red Tape: Parking permits/shuttle reservations are required to access the trailhead, as are permits to camp overnight on the trail.

Getting There

Aspen is accessible by car or via the Aspen Airport. Unfortunately, accessing the trail in the first place may be the most difficult part of a trip to the Four Pass Loop. Unless you’re willing to add mileage, there is only one trailhead to start the trail — the Maroon Lake Trailhead, which is #2197. This trailhead is within the Maroon Bells Scenic Area, which is regulated from May through October, so you have a few choices:

1. Buy a multi-night backpacker’s parking permit for the scenic area. These permits go fast, so you must plan far in advance. In addition, the max time you’re allowed to park at the trailhead is 2 days/60 hours, which would be a tight timeline for this loop. Unless you’re willing to go that fast, you’re better to …

2. Book a shuttle from Aspen Highlands. You’ll need to park in Aspen (currently, there are a few free parking lots on the edge of town where a bus can pick you up, specifically Brush Creek Park & Ride, though this is subject to change) and navigate the free bus system to get to the transfer station at Aspen Highlands. From there, you’ll take your reserved shuttle up to the trailhead. It’s a complicated system, but such is the nature of popular mountain towns. 

3. Add mileage to your trip and skip Maroon Lake TH altogether. Click or scroll down for more information on this option. 

Stop by downtown Aspen on your day to or from the trail! YOLO!

If you choose to visit the Maroon Bells Scenic Area, visit the official website to reserve a ticket or permit for parking/shuttles. The system changes a little bit each year, so be sure to reference the current information there.

Red Tape: Trail Permits

Unfortunately, this trail requires overnight permits since it runs entirely within the Maroon-Snowmass Wilderness. Technically, there’s no permit to hike the trail, just to camp overnight within the wilderness. The Four Pass Loop traverses five different permit zones, so you’ll have to plan where you want to camp each night and book permits accordingly. The zones are as follows: Maroon, East Fork, North Fork, Snowmass Lake, and Upper Snowmass (Crater Lake is also a zone, but almost no backpackers camp there). Here’s the Forest Service’s map for clarity:

Via the US Forest Service. To view a larger map of the entire wilderness, click here. The yellow dashed line is the Four Pass Loop.

There are viable campsites in each zone, so your camping situation may depend on which zones have availability for the day you will pass through them. To view available permits and book them, visit recreation.gov. Permits until July 31 are typically released in early February, and permits until November 30 are typically released in early June. For this trail, it pays to plan ahead so you don’t get stuck with a weird permit situation.

Photo via.

Direction and Trail Layout

An overview map of Four Pass Loop. (© OpenStreetMap contributors) Wanna look at this map closer? Check it out on Caltopo here.

The Four Pass Loop can be hiked in either direction, though most hike clockwise — this direction offers better views of Snowmass Lake descending and of the Maroon Bells. Going in this direction (and starting from the West Maroon Trailhead), hikers face West Maroon Pass, Frigid Air Pass, Trail Rider Pass, and Buckskin Pass, in that order. Other than that brief overview, there’s little more to talk about layout. 

Wanna skip parking permits? A side note:

There are several options for you if you want to skip the crazy parking/shuttling situation of Maroon Lake Scenic Area. (Check out this map for more granular details on these routes.) Remember that by skipping parking permits you’re still required to get trail overnight permits to camp on the trail. 

1. Start the trail from Crested Butte: Unless you have a high-clearance 4WD vehicle, this option is not a viable one for your trip — the roads are very difficult. From Crested Butte, you can access the loop via East Fork TH or Geneva Lake TH on the backside. Both trailheads add marginal mileage (~3 miles). 

2. Hike-in to the trail from Snowmass Village: From Snowmass TH in Snowmass Village, you can access the loop via two trails. The first option is the Maroon-Snowmass Trail, an eight-mile one-way hike-in to the Four Pass Loop. With this option, you join the loop at Snowmass Lake and must gain an additional 2,700 feet.

The second option is the East Snowmass and Willow Lake Trails, which together form a more adventurous hike-in route, involving an additional pass, Willow Pass, plus 9.25 miles and nearly 5,000 feet of gain. It joins the loop just below Buckskin Pass. The advantage to these routes as opposed to Maroon Lake’s shuttle/parking situation is free, unlimited parking and more freedom. Obviously, they require more research and aren’t for everyone. Use your best judgment here. 

By taking alternate routes, you’ll start lower in elevation, in forests like this scene near Snowmass Village.

Why Hike the Four Pass Loop?

The Four Pass Loop is a well-built trail that routes through some of the most scenic terrain in the United States. There’s a reason it’s so popular. The Elk Mountains, with their red-purple craggy rock, bright green forests, abundant wildflowers, and crystal-clear lakes, strike many as the most beautiful part of Colorado, which is already a very beautiful state.

On this trail, you also hike in the shadow of many of the highest of the rocky mountains, including several “14ers” (mountains over 14,000 feet). The Four Pass Loop epitomizes the slogan “Colorful Colorado.” It’s also just a really good and convenient trail. At only 26 miles, it’s a good introduction to backpacking in the high mountains, and as a loop, logistics are much easier than point-to-point shuttle coordinating.

While its popularity throws some challenges, Four Pass Loop is still very much a worthwhile trail to put on your bucket list.

Photo via. One of many beautiful scenes in the Maroon Bells-Snowmass Wilderness.

Climate and Weather

Sitting on average 11,100 feet above sea level, the weather on this trail is no joke. Deep snowpack, avalanches, and unexpected snowstorms persist into June every year, and winter starts again in late October/early November. During hiking season, highs will typically run in the 50s or 60s with nighttime lows in the 20s or 30s.

However, most concerning to hikers is the threat of lightning. From late June through September, the monsoon brings violent thunderstorms nearly every afternoon to the high country. This trail brings you exactly where you don’t want to be in the case of a storm, so you’ll have to take extra precautions to stay safe from lightning. First and foremost, if black, stormy clouds are building or you hear thunder, do not attempt to go over a pass, even if you are a good way up already.

Imagine this: you’re tired, you’ve been hiking all day, and camp is just on the other side of the pass. You’re sooooo close, so you decide to ignore the rumbles of thunder you hear at your back. They sound far off, but as you approach the top of the pass, a storm rolls over, and suddenly you’re in hell: your hair stands on end, lightning crashing all around, torrential rain mixed with hail and sleet beating down, etc.

That, my friends, is how people die. You can avoid the unfortunate reality of running back down the pass you worked so hard to climb up by planning to hike your big stretches above treeline in the morning. Aim to summit your pass(es) each day by 11 a.m. and you should largely avoid storms. However, the weather in the high mountains is highly unpredictable, so use your best judgment. 

Weather in the high country is unpredictable and can produce powerful snowstorms like this one year-round (taken in July). It pays to be prepared so you don’t get in a bad situation.

Four Pass Loop Gear Suggestions

You might be tempted to think that the Four Pass Loop, as a relatively short trail, gives you a little more leeway on pack weight. While this may be true for advanced backpackers who are already acclimated to high altitude, the vast majority of FPL hikers should go as lightweight as possible. Why? 8,000 feet of vertical gain is no joke, especially at 12,000 feet. Bring your normal backpacking gear kit (this gear list for the Colorado Trail should help with specific gear suggestions). Here are a few notes to point out for this route: 

1. A rain jacket is an absolutely essential piece of gear for any excursion in the Colorado high country, but especially this trail which brings you frequently above treeline. If you’ve been on the fence about investing in a good rain jacket, here’s your sign to upgrade. Trust me, taking a “water-resistant” windbreaker and calling it good is NOT the way to go. 

2. IGBC-approved bear-resistant food storage containers are required in the Maroon Bells-Snowmass Wilderness. You can rent them from some outfitters in Aspen and nearby towns, but you have to have one. Note that Ursacks are still allowed under these requirements. 

3. While they aren’t technically required, the Forest Service highly recommends using WAG bags to pack out human waste in this area, given its popularity and alpine environment. They are available for free at the Maroon Lake Scenic Area Trailhead. If you choose not to use WAG bags, you are still required to pack out paper waste because this is designated wilderness. (Also, it’s just good practice!)

4. Bring a stove setup or some means to cook meals without the use of campfires. Not only are campfires very harmful to the alpine landscape, but they are also very dangerous in such a wildfire-prone place as Colorado. In addition, in most of the campsites on the Four Pass Loop, it’s actually illegal to have campfires anyway. Do yourself and Colorado a favor, and pack a stove instead of relying on fire to cook.

Every year, wildfires in Colorado and the wider Western US devour thousands upon thousands of acres of forests and people’s homes and livelihoods. Many of those, like the Interlaken fire of summer 2024, are caused by campfires not fully extinguished. Please, on behalf of those who live where you’re recreating, choose not to have a fire at all, or if you must, make sure you know how to fully extinguish it.

Camping

Camping will be what you plan your hike of Four Pass Loop around. While campsites are not technically designated, as I discussed earlier in the permits section, you’ll still have to plan which permit zone you’ll camp in each night. For a list of campsites, take a look at this Forest Service inventory or the guide on FarOut.

While planning your hike, keep in mind that due to the popularity of this loop, you may have to camp at a different campsite than planned. Most groups, if they hike clockwise, will camp in the Maroon, North Fork, and Snowmass Lake zones (in that order). Snowmass Lake, in particular, is a standout camping location. 

Highlights of the Four Pass Loop

Four Pass Loop passes by many high-profile scenic locations. There is the famous Maroon Bells and Maroon Lake, the most photographed mountains in Colorado. Snowmass Lake, an incredibly scenic alpine lake clocking in at over 100 feet deep, is on the loop and is a popular camping location.

Every pass, you’ll go over sports 360-degree views of the surrounding landscape. 14ers Pyramid Peak, the Maroon Bells, and Snowmass Mountain are all closely visible, granting you views of some of the most impressive mountains of Colorado.

Honestly, this entire trail is one big highlight reel, so it’s hard to pick out specific spots over others. On this trail, enjoy the privilege of being in such a special place. It doesn’t disappoint.

The famed Maroon Bells are a standout feature of Four Pass Loop. Photo: Rhododendrites, CC BY-SA 4.0, via Wikimedia Commons

Water Sources

Water is plentiful in the high mountains of Colorado. On this loop, passes and ridgetops are dry, but every valley has a strong stream flowing through it. This means that you’ll never be more than four miles from water at any point on the loop (under usual conditions). Unless your team plans on dry camping, you shouldn’t need more than two liters of water per person to get you through the brief dry stretches.

Earlier in the season, you may have to melt some snow, so a stove would be useful to bring. As a reminder, while water in the high alpine may seem very clean, you should filter/treat all water except freshly melted snow for safety.

This is pretty much the only situation that you wouldn’t be right next to water. (but hey, there’s even an alpine lake if you get in a pinch!) Photo: Troy Zohner.

Closing Thoughts

The Four Pass Loop is a world-class short loop trail that is a suitable introduction to backpacking in the alpine. While the permit situation may be difficult to navigate, the rewards of this trail far outweigh the challenges. There are few trails so logistically easy that offer access to such incredible terrain. Knock the Four Pass Loop off of your bucket list and enjoy some of the best that Colorado has to offer!

Get out there!

Featured image: Photo via Kendyl McAlister; graphic design by zZack Goldmann.