Arapaho Glacier Trail
The Arapaho Glacier Trail is a long, strenuous hike along a high, exposed ridge in the Indian Peaks Wilderness to an overlook of Arapaho Glacier, often called Colorado's largest glacier. Much of the route borders the City of Boulder Watershed, which is closed to public entry, so you stay on the trail the whole way.
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Arapaho Glacier Trail quick facts
- Distance
- About 7.4 miles round trip from the Fourth of July Trailhead (the western approach), or about 12 miles round trip from the Rainbow Lakes Trailhead (the eastern approach), per the Colorado Mountain Club.
- Elevation gain
- About 2,600 feet from the Fourth of July Trailhead, or about 3,130 feet from Rainbow Lakes, per the Colorado Mountain Club.
- High point
- The Arapaho Glacier Overlook, at about 12,700 feet (the Colorado Mountain Club lists a high point of 12,730 feet).
- Difficulty
- Strenuous. It's a long hike at high altitude, much of it on an open ridge above treeline with little or no shelter.
- Access
- Two trailheads. From the west, the Fourth of July Trailhead by way of the Arapaho Pass Trail (#904); from the east, the Rainbow Lakes Trailhead. Both sit at the end of rough dirt roads, and the Forest Service recommends a high-clearance vehicle for the Rainbow Lakes road.
- Watershed
- Much of the route borders the City of Boulder Watershed, which is closed to public access. As the Forest Service posts it, do not leave the trail or enter the watershed.
- Dogs
- Allowed, but pets must be on a hand-held leash at all times. This is Indian Peaks Wilderness, so leash rules are enforced.
- Best season
- July through September, sometimes into October in a dry year, the short window when the high country is usually clear of snow. Start at dawn to be off the ridge before afternoon storms build.
Arapaho Glacier Trail at a glance
The Arapaho Glacier Trail is one of the bigger days you can have close to Boulder. It climbs onto a high, open ridge in the Indian Peaks Wilderness and ends at the Arapaho Glacier Overlook, a viewpoint above Arapaho Glacier, which sits in a cirque southeast of North Arapaho Peak. Arapaho Glacier is the largest glacier in Colorado and has long helped supply water to the city of Boulder. From the overlook you look down on the glacier, South Arapaho Peak, and North Arapaho Peak, with the plains far to the east.
The City of Boulder Watershed is closed. Stay on the trail.
This is the single most important rule on the trail. Much of the route runs right along the boundary of the City of Boulder Watershed, and the Forest Service posts that land as closed to public access. Their own trail description is blunt about it: as posted, the area is closed, and you should not trespass. That means you stay on the trail the entire way and do not drop off the ridge toward the glacier or the watershed lakes, no matter how inviting the view looks. The overlook is a place to look, not a way in.
How far, how high, and how hard
There are two approaches, and the numbers depend on which one you pick. From the west, starting at the Fourth of July Trailhead, you hike the Arapaho Pass Trail for about two miles to the junction with the Arapaho Glacier Trail near the remains of the Fourth of July Mine, and the overlook is about 3.7 miles from the trailhead, roughly 7.4 miles round trip with about 2,600 feet of climbing. From the east, the Rainbow Lakes Trailhead reaches the same overlook in about 6 miles, roughly a 12-mile round trip with about 3,130 feet of gain. Those figures come from the Colorado Mountain Club. Either way you top out near 12,700 feet, so treat this as a strenuous, high-altitude outing, not a casual afternoon walk.
Storms and the exposed ridge: start early
The upper trail is a long stretch of open tundra and ridge with almost no shelter, and that is exactly where you do not want to be during a Colorado afternoon thunderstorm. Lightning above treeline is a real hazard. The fix is simple and non-negotiable: start at first light, move steadily, and plan to be off the high ridge and heading down before the clouds build, which often means turning around by early afternoon whether or not you have reached the overlook. See our guide to thunderstorm safety before you go.
Getting there and the trailheads
Both trailheads sit at the end of rough mountain roads. The Fourth of July Trailhead is reached from Nederland through Eldora and up a long, rough dirt road; see our Fourth of July Trailhead guide for directions and parking. For the eastern approach, the Forest Service directs you from Nederland north on Colorado Highway 72 for about seven miles to the University of Colorado Mountain Research Station sign, then west onto Forest Road 298, a five-mile native-surface road where a high-clearance vehicle is recommended. Neither road is a place to be in a hurry.
Wilderness rules and permits
The trail is inside the Indian Peaks Wilderness, so the usual wilderness rules apply. Motorized equipment and mechanized transport (including bikes) are prohibited, dogs must be on a hand-held leash at all times, campfires are prohibited year-round, and group size is limited to 12 people and stock combined. If you plan to stay overnight, the Forest Service requires a camping permit for overnight trips between June 1 and September 15, with a small per-group fee. Most people do the overlook as a long day hike and do not need a permit for that.
Best season and time to go
The realistic window is July through September, sometimes stretching into October in a dry year, which is when the high country is generally clear of snow and the road is open. Snow can linger on the upper switchbacks well into summer, and it returns early in the fall. Whatever the month, the day starts early: the earlier you are on the trail, the better your odds of clear skies at the overlook and a safe walk back down.
Nearby trails and guides
- Fourth of July Trailhead: the western gateway to this hike, with the road, parking, and other trails from the same lot.
- Thunderstorm safety: how to time an above-treeline day and what to do when the sky turns.
- All hikes in Boulder: the full hiking hub, sorted by difficulty.
Recommended nearby
A few local spots we'd point a high-country day toward.
[CLIENT SLOT: featured gear shop near Nederland]
[One honest line: layers, traction, and the ten essentials for an above-treeline day.]
[CLIENT SLOT: featured cafe in Nederland]
[One honest line: an early breakfast or coffee before the drive up the rough road.]
[CLIENT SLOT: featured lodging near Nederland]
[One honest line: a place to stay so you can hit the trailhead at dawn.]
Arapaho Glacier Trail FAQ
How do you get to the Arapaho Glacier Overlook?
There are two ways in. From the west, most hikers start at the Fourth of July Trailhead and take the Arapaho Pass Trail for about two miles to the junction with the Arapaho Glacier Trail near the old Fourth of July Mine; the overlook is roughly 3.7 miles from that trailhead, about 7.4 miles round trip. From the east, the Rainbow Lakes Trailhead reaches the same overlook in about 6 miles, roughly a 12-mile round trip, per the Colorado Mountain Club.
Can you hike onto Arapaho Glacier or into the City of Boulder Watershed?
No. Much of the trail borders the City of Boulder Watershed, and the Forest Service posts it as closed to public access with a clear instruction not to trespass. Stay on the trail and do not drop into the basin toward the glacier or the watershed lakes. The overlook is exactly that: a viewpoint above a closed area, not an access point to the glacier.
How long and strenuous is the Arapaho Glacier Trail?
It's a strenuous high-country hike. From the Fourth of July Trailhead it's about 7.4 miles round trip with roughly 2,600 feet of elevation gain; from Rainbow Lakes it's about 12 miles round trip with roughly 3,130 feet of gain, per the Colorado Mountain Club. Either way you finish above 12,000 feet, and much of the upper route is exposed tundra and ridge.
When should you hike it, and why start so early?
July through September is the reliable window, occasionally into October in a dry year. Start at first light. The upper trail is a long, open ridge above treeline with almost no shelter, and Colorado's afternoon thunderstorms bring lightning that is dangerous in the open. The goal is to reach the overlook and be heading down before storms build, usually by early afternoon.
Are dogs allowed on the Arapaho Glacier Trail?
Yes, but dogs must be on a hand-held leash at all times. The trail runs through the Indian Peaks Wilderness, where the Forest Service enforces leash rules along with a ban on motorized and mechanized travel, year-round campfire restrictions, and a group-size limit of 12.
Sources
Facts on this page are drawn from these authoritative sources: