Trails · Rocky Mountain National Park · Longs Peak
Chasm Lake Trail
A strenuous alpine classic to an 11,760-foot lake set directly beneath the sheer 1,000-foot east face — the Diamond — of Longs Peak. One of the most jaw-dropping lake basins in Colorado.
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Chasm Lake gives you the grandeur of Longs Peak without the summit's technical climb. From the Longs Peak trailhead, the route climbs the East Longs Peak Trail through forest and then out above treeline, with the mountain growing ahead the whole way. It passes the turnoff for the Longs Peak summit and traverses a shelf above a deep gorge, looking down on the glittering Peacock Pool and the ribbon of Columbine Falls at the head of the valley.
A short spur leaves the Longs Peak route at about 3.2 miles and climbs the last stretch — over boulders and stone steps, with a bit of easy scrambling near the end — to Chasm Lake at 11,760 feet, cupped in a rock bowl directly beneath the Diamond, the sheer 1,000-foot east face of Longs Peak. It's about 8.4 miles round trip with roughly 2,360 feet of gain, most of it above treeline. National Park land: no dogs, and this is serious high country — start before dawn to beat the storms.
Trail Facts
Difficulty
Difficult (strenuous, high altitude)
Round trip
~8.4 mi via the Longs Peak Trail
Lake elevation
11,760 ft
Elevation Gain
~+2,360 ft
Bikes
Not allowed (National Park)
Dogs
Not allowed (National Park)
Season
Summer–early fall (snow lingers)
Highlights
Peacock Pool · Columbine Falls · the Diamond
Manager
Rocky Mountain National Park
Getting There
From Estes Park, take Highway 7 south about 9 miles to the Longs Peak Trailhead (Longs Peak Ranger Station). Follow the East Longs Peak Trail; past the Chasm Lake junction (~3.2 mi) take the spur to the lake. The lot fills in the middle of the night on summer weekends — arrive very early. No timed-entry is needed for the Longs Peak corridor, but parking is the limiter.
| 0.0 mi | Longs Peak Trailhead (Hwy 7) |
| ~2.5 mi | Above treeline — Longs Peak ahead |
| 3.2 mi | Chasm Lake junction (Longs Peak summit route continues right) |
| ~3.5 mi | Shelf above Peacock Pool & Columbine Falls |
| 4.2 mi | Chasm Lake, 11,760 ft — beneath the Diamond |
Know Before You Go
- Start before dawn. Most of the route is above treeline — be heading down before midday thunderstorms, which are lethal up here.
- Parking is the crux. The Longs Peak lot fills in the small hours on summer weekends; plan a very early start.
- Real alpine. Big elevation, thin air, boulders and a little scrambling near the lake — be fit and acclimated.
- No dogs. National Park land — dogs are not allowed.
- Snow lingers. Expect snow near the lake into summer; check conditions and carry traction in shoulder season.
Built by Many Hands — Give a Little Back
Love this guide? Wear it. Every hat, tee, and cozy layer in our Red Feather Lakes collection helps us keep mapping trails and keeping this guide free — mountain apparel designed right here in the high country, with more trail gear on the way.
Shop the Collection →These trails don't tend themselves either. Every mile is watched over by volunteers and public stewards we lean on to bring you this guide — if you love these mountains, please pitch in for them too:
- Poudre Wilderness Volunteers — trail patrols & the official trail description Donate →
- Colorado Parks & Wildlife / COTREX — the mapped trail route & statewide trail data Donate →
- Arapaho & Roosevelt National Forest (USFS) — the public land itself Support →
- OpenStreetMap contributors — the Street basemap Donate →
- Google & USGS — trailhead location, ratings & topographic maps
Trail details compiled by the Red Feather Lakes Travel Guide from the sources above. Photography by us — more of our own trail images coming as we hike them.