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Chasm Lake

Rocky Mountain National Park

Hike up into the treeless tundra, to a glacial lake tucked beneath a 14-thousand-foot peak.

Hiking Difficult

13 km
776 m
776 m
3-4 hrs
Low Point
2.9 km
High Point
3.6 km
Chasm Lake Map

Chasm Lake is just below the sheer east face of Longs Peak, which is the tallest mountain in Rocky Mountain National Park. To reach Chasm Lake, you’ll begin on the same trail which leads to Longs’ 14-thousand-foot summit. The first couple of miles are steadily uphill, on a well-trodden path through evergreen forest. Eventually, the trail emerges from the trees, onto alpine tundra dotted with squat spruce and colored with wildflowers. This is where views really open up, of the peaks above and more mountains all around.


Eventually, the trees disappear altogether, and the trail steepens on very rocky terrain. At a well-signed junction, the route to Longs Peak splits to the right, and the trail to Chasm Lake goes left. By this point, most of the elevation gain is over with, and the trail contours around a ridgeline, overlooking a steep valley where small lakes and a waterfall are seen below.

One obstacle stands in the way of Chasm Lake, however: it’s a steep section of rock rubble which must be scrambled. Intimidating but not too difficult, the route follows a path of least resistance through talus and up a natural ramp. At the top is the lake, with sparkling water framed dramatically beneath the vertical walls of Longs Peak. Smooth boulders around the shoreline provide places for lounging and soaking in the views.

Note that because this trail is so high and exposed, weather can quickly become extreme and dangerous. In the summer, thunderstorms commonly pop up in the afternoon, so you should start hiking very early in order to beat the storms. The parking lot often fills up well before sunrise, however, with hikers attempting Longs. Consider alternate transportation to the trailhead if visiting during the busy season.

Sources: https://www.nps.gov/thingstodo/romochasmlake.htm https://www.earthtrekkers.com/chasm-lake-hike/



Hiking trails where obstacles such as rocks or roots are prevalent. Some obstacles can require care to step over or around. At times, the trail can be worn and eroded. The grade of the trail is generally quite steep, and can often lead to strenuous hiking.

High Exposure

3 out of 4

Some trail sections have exposed ledges or steep ascents/descents where falling could cause serious injury.


3 out of 4

Little chance of being seen or helped in case of an accident.

Best time to visit

between May and November


  • Alpine
  • Wildlife
  • Picturesque
  • Wild flowers
  • Water features
  • Forestry or heavy vegetation

Similar routes nearby

Guidebooks in this area