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blueBlack Chasm Lake

  4.7 ( 59 ) Favorite

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8.2 mile 13.3 kilometer out and back


Ascent: 2,766' 843 m
Descent: -2,766' -843 m
High: 11,675' 3,559 m
Low: 9,430' 2,874 m


Avg Grade: 13% (7°)
Max Grade: 50% (26°)


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Trail shared by Brian Smith

A must-do RMNP hike that leads to and from an incredible alpine lake.

Brian Smith

Features Birding · Lake · River/Creek · Views · Wildflowers · Wildlife


This hike offers many of the draws of the Longs Peak hike in a much shorter, easier to manage package. Although you'll not achieve the same "top of the world" views on offer from Longs Peak, you'll still work for some stunning views from an alpine glacial tarn.

Need to Know

Given that the exceedingly popular Longs Peak hike originates from the same trailhead, be prepared for crowds. The Longs Peak Trailhead can also fill up quickly on nice days, so plan to start early if possible.

Once you get out of the subalpine forest, there is very little shade or protection from the wind so use the sunscreen and have the lip balm handy. Even in the summer months, a lightweight long-sleeve shirt is recommended.


Start hiking up the Longs Peak Trail from the trailhead. The trail is rocky and has steps created by trail crews the whole way. It is moderately steep as it switchbacks its way to a junction with Eugenia Mine Trail, roughly 0.5 miles in. Longs Peak Trail continues ascending above Alpine Brook, eventually crossing it at mile two. Shortly thereafter, you'll reach a junction with Jims Grove Trail and begin to emerge above tree line. Continue on Longs Peak Trail for another 0.8 miles to the Chasm Lake Trail. Turn right onto Chasm Lake Trail.

This trail contours gently along the south face of Mills Moraine providing excellent views below of Peacock Pool and Columbine Falls along the Roaring Fork river. The gentle positive grades give way to equally gentle negative grades before the trail shows its second, and much more drastic character.

After crossing the upper reaches of the Roaring Fork River, at roughly mile 3.7, this trail begins to climb very steeply and will require some scrambling up the outer side of the "wall" that holds the lake.. This short but strenuous pitch is well worth it as you are quickly rewarded with the absurd views at Chasm Lake.

From the lakeshore, you'll be able to view the majestic "Diamond," one of the steepest and most iconic rock faces in Colorado. Located on the east face of Longs Peak, The Diamond rises roughly 2400' straight up.

There are privies located approximately at the intersection of Chasm Lake Trail and Longs Peak - Keyhole Route and also just below Chasm Lake next to a Ranger station (small rock building) in the marshy area,

Flora & Fauna

This hike begins in a subalpine ecosystem which occupies elevations approximately between 9,000 and 11,000 feet. A typical subalpine forest may consist mostly of subalpine fir and Engelmann spruce. as you transition above treeline, you'll be entering the alpine ecosystem.

Here, many plants are dwarfed, but their few blossoms may be full-sized. Cushion plants, looking like ground-hugging clumps of moss, escape the strong winds blowing a few inches above them. Cushion plants may also have long taproots extending deep into the rocky soil. Many flowering plants of the tundra have dense hairs on stems and leaves to provide wind protection or red-colored pigments capable of converting the sun's light rays into heat.

Keep a close look in the marshy area between the lakes for the fast moving Pika, resembling a small rabbit with short ears and the lumbering marmot that resembles a beaver with a fox tail. The pika usually makes a short squeaking sound as it initiates its movements.

History & Background

Chasm Lake sits in a semi-circular, steep sided scar, known as a cirque, that is indicative of the top of a glaciated valley. A moraine (as in Mills Moraine) is a field of debris left behind by a glacier as it melts that it scraped and tore from the walls of the valley it moved down.


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May 14, 2019
Emory Walls
Beautiful hike up to the lake, however the trail is almost completely snow packed. Made the hike quite strenuous! 8.2mi — 4h 30m
Mar 21, 2019
Thomas S
Beautiful. Last .5mi tricky but fun. — 5h 00m
Feb 3, 2019
Sunshine Silvernale
Oct 28, 2018
Seth Dayvan
from the boulder field to chasm lake is one of the most beautiful areas I’ve seen in Colorado. 8.2mi
Oct 26, 2018
Marian Van Vlack
Oct 25, 2018
Alex Yates
Oct 20, 2018
Felipe Tranquilini
Great hike with amazing views!!! Fairly easy, but long with good elevation gains. A bit icy in late October, so bring your yaktracks unless you wan… 8.2mi
Oct 6, 2018
Sierra James

Trail Ratings

  4.7 from 59 votes


  4.7 from 59 votes
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