Diamond Lake
Diamond Lake is an alpine lake at 10,940 feet in the Indian Peaks Wilderness, reached on a roughly 5.4-mile round-trip hike from the Fourth of July Trailhead above Eldora, past a creek crossing and a waterfall to some of the best summer wildflowers on the Front Range.
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Diamond Lake quick facts
- Distance
- Roughly 5.4 miles round trip. The Forest Service does not publish a single loop figure; it describes the route in segments: 1.2 miles up the Arapaho Pass Trail to the Diamond Lake Trail, about half a mile down to the creek crossing, then a mile up to the lake, and back the same way.
- Elevation gain
- About 900 feet net from the trailhead (around 10,100 feet) up to the lake, with extra up-and-down because the Diamond Lake Trail drops to cross the creek before climbing to the lake.
- Lake elevation
- 10,940 feet at Diamond Lake, per the Forest Service.
- Difficulty
- Moderate. It's a high-altitude hike with a creek crossing and a northeast-facing slope that holds snow well into summer.
- Access
- From the Fourth of July Trailhead above Eldora. From Nederland, take Colorado 119 south 0.5 mile, turn west on Boulder County Road 130 toward Eldora, and stay on the main road through the town of Eldora. Once the pavement ends, continue about five miles of rough dirt road to the trailhead. Parking is limited and fills early on summer weekends.
- Dogs
- Allowed, but they must be on a hand-held leash at all times. That's the Indian Peaks Wilderness rule, and it applies the whole way.
- Permits
- No day-use permit for groups of one to seven. Overnight backcountry camping in the Diamond Lake zone needs a permit from June 1 through September 15 ($5 Forest Service fee plus a $6 recreation.gov reservation fee), camping is designated-sites-only, campfires are prohibited year-round, and a bear canister is required.
- Best season
- July through September. Snow lingers on the shaded slope into early summer, and the wildflowers are usually at their best in mid- to late July.
Diamond Lake at a glance
Diamond Lake is a classic Indian Peaks day hike: a high alpine lake at 10,940 feet, tucked below the Continental Divide, reached from the Fourth of July Trailhead above the little town of Eldora. It's the kind of hike people drive up for on purpose in July, when the meadows along the North Fork of Middle Boulder Creek fill in with wildflowers and the creek is loud with snowmelt. It's real mountain terrain, not a foothill stroll, so it rewards an early start and a little planning.
The hike from the Fourth of July Trailhead
From the trailhead, the Arapaho Pass Trail enters the Indian Peaks Wilderness and climbs for 1.2 miles to the junction with the Diamond Lake Trail. The Diamond Lake Trail forks left and drops elevation for about half a mile before crossing the North Fork of Middle Boulder Creek on a bridge near a scenic waterfall. From there it's roughly a mile further uphill to the lake, on a northeast-facing slope that holds snow long after the sunnier Arapaho Pass Trail has melted dry. Turn west on the marked side trail to reach Diamond Lake itself. Add it up and back and you're looking at about 5.4 miles round trip.
The road and parking
Getting to the trailhead is half the adventure. From Nederland, head south on Colorado 119 for half a mile, then turn west onto Boulder County Road 130, signed for Eldora Ski Resort. Stay on the main road right through the town of Eldora. Where the pavement ends, keep going about five more miles of dirt to the Fourth of July Trailhead. The Forest Service describes this stretch as rough but passable in a passenger car during the summer months, so take it slow. Parking at the trailhead is limited and fills early on summer weekends, which is one more reason to start at first light.
Permits, dogs, and wilderness rules
For day hiking, a group of one to seven people needs no permit at all. Only large groups of 8 to 12 need a day-use permit for the zone. If you plan to camp, you do need a backcountry permit for the Diamond Lake zone from June 1 through September 15, and camping at Diamond Lake is restricted to designated sites. Campfires are prohibited year-round here, and because this is the Diamond Lake backcountry zone, a bear canister is required for food storage. Dogs are welcome, but they must be on a hand-held leash at all times in the Indian Peaks Wilderness. Motorized and mechanized travel, including bikes, is not allowed past the wilderness boundary.
Wildflowers, the waterfall, and the creek
The draw here is the water and the flowers. The Diamond Lake Trail drops to cross the North Fork of Middle Boulder Creek right by a waterfall, and the meadows on the climb to the lake are some of the more reliable wildflower displays in the Boulder high country. They're usually at their best in mid- to late July, though it swings a week or two either way depending on the winter's snowpack. Bring a layer: the lake basin is exposed, and afternoon thunderstorms are common in summer, so plan to be heading down by early afternoon.
Best season and time to go
Plan on July through September. Because the creek-crossing stretch faces northeast and stays shaded, it can hold snow into early summer even when the lower trail is dry, so early July hikers should be ready for a lingering snowfield near the bridge. For the wildflowers, aim for mid- to late July. For quieter trails and gold aspen lower down, September is hard to beat. Any time of year, go early: the parking fills, and the weather turns in the afternoon.
Nearby trails and guides
- Brainard Lake: the other great Indian Peaks basin north of here, with easier lake hikes and a timed-entry reservation system.
- Nederland: the mountain town you'll pass through, and the last stop for coffee, food, and supplies before the dirt road.
- All hikes in Boulder: the full hiking hub, sorted by difficulty.
Recommended nearby
A few local spots we'd point a Diamond Lake day toward.
[CLIENT SLOT: featured outdoor shop near Nederland]
[One honest line: bear canister rental, layers, or trail supplies before you drive up.]
[CLIENT SLOT: featured cafe in Nederland]
[One honest line: breakfast or coffee on the way to the trailhead.]
[CLIENT SLOT: featured stay near Nederland or Eldora]
[One honest line: a place to base an early start.]
Diamond Lake FAQ
How far is the hike to Diamond Lake?
It's roughly 5.4 miles round trip from the Fourth of July Trailhead. The Forest Service describes it in pieces rather than as one number: the Arapaho Pass Trail climbs 1.2 miles into the Indian Peaks Wilderness to the Diamond Lake Trail, which forks left and drops about half a mile to cross the North Fork of Middle Boulder Creek, then it's a mile further uphill to the lake. You return the same way.
Do you need a permit to hike to Diamond Lake?
Not for day hiking in a group of one to seven, from June 1 through September 15 or the rest of the year. Only large groups of 8 to 12 need a day-use permit. If you want to camp overnight, you do need a backcountry permit for the Diamond Lake zone between June 1 and September 15, and camping at Diamond Lake is restricted to designated sites.
How do you get to the Fourth of July Trailhead, and what is the road like?
From Nederland, head south on Colorado 119 for half a mile, turn west onto Boulder County Road 130 (signed for Eldora Ski Resort), and stay on the main road through the town of Eldora. Where the pavement ends, keep going about five more miles to the trailhead. The Forest Service calls this dirt stretch rough but passable in a passenger car during the summer. Parking at the trailhead is limited and fills up early on summer weekends.
Are dogs allowed at Diamond Lake?
Yes, but dogs must be on a hand-held leash at all times in the Indian Peaks Wilderness, the whole way to the lake. This isn't a voice-and-sight area like some Boulder foothill trails, so plan to keep your dog physically leashed.
When is the best time to hike to Diamond Lake for wildflowers?
July through September is the reliable window. Diamond Lake sits at 10,940 feet on a northeast-facing slope that holds snow long after the sunnier Arapaho Pass Trail has melted out, so the creek-crossing stretch can stay snowy into early summer. The wildflowers are usually at their peak in mid- to late July, alongside the creek and its waterfall.
Sources
Facts on this page are drawn from these authoritative sources: