How to Hike Chasm Lake: Helpful Tips, Hiking Stats & Photos

The hike to Chasm Lake is challenging but it rewards you for your effort. If you have plans to spend several days in Rocky Mountain National Park and you are a hiker, this is one of the best trails to put on your to-do list.

Chasm Lake Hiking Stats

Distance: 8.2 miles out-and-back
Starting Elevation: 9,400 feet 
Highest Elevation (Chasm Lake): 11,800 feet
Total Ascent: 2,700 feet
Difficulty: Strenuous
Length of Time: 4 to 6 hours
When to Go: The best time to do this hike is from June through September, when the trail is free of snow. Snow can linger on trail into July. Get updates on trail conditions on the National Park Service website.
Timed Entry Permit: Park Access permit (the permit that does not include Bear Lake Road).

Chasm Lake elevation profile

How to Hike to Chasm Lake

Step-By-Step Trail Guide

Trailhead: Longs Peak Trailhead

The hike starts at the Longs Peak Trailhead. To get here, take Highway 7 and turn onto Longs Peak Road. At the end of this road is a parking lot that can hold approximately 20 cars. Overflow parking tends to line the road as you approach the parking lot.

Hikers that are attempting to summit Longs Peak start at the same trailhead and park in the same parking lot. Due to the distance of the Longs Peak hike, most hikers arrive between 3 and 5 am to start their hike. We spoke to a park ranger who stated that the lot can be completely full by 2 am!! Car camping is not permitted in this lot.

The four of us had no desire to arrive by 2 am to get a space. So, Tim dropped me and Kara off, and just the two of us hiked to Chasm Lake. Meanwhile, Tim and Tyler hiked Twin Sisters and then picked us up after their hike.

When we arrived in the parking lot, at about 6:30 am, every space was filled and there were many cars on the roadside. We probably would have gotten away with also parking on the road but didn’t want to take the chance of getting a ticket. So, we split up.

Kara and I definitely did the better hike. Chasm Lake is amazing!!

Chasm Lake and Longs Peak trailhead

On the Trail to Chasm Lake

For the first 2 miles you will hike through a fir and pine forest. It is a steady, uphill hike the entire way. In fact, there are very few flat sections or downhill sections as you hike to Chasm Lake. This is a tough hike.

Trail junctions are well marked with signs throughout the hike.

At about the 2-mile point, you emerge from the forest and begin hiking in the subalpine tundra. Once out of the trees, you get panoramic views of the mountains surrounding trail. In front of you is the massive peak of Longs Peak. Behind you are the Twin Sisters.

The stretch of trail from the edge of the forest to the trail junction for the Keyhole Route is one of the most strenuous of the hike. The trail rapidly gains elevation and you will hike up and over massive boulders and stone steps. At least the view is great, as you get closer to Longs Peak.

Chasm Lake – Longs Peak Junction

3.3 miles into the hike you reach the trail junction. There are toilets here. Go left to continue on to Chasm Lake. Those hiking to Longs Peak will go right through the Boulder Field.

This is the point where the hike really gets good. You have covered most of the elevation gain by this point and what lies in front of you are some of the best views in Rocky Mountain National Park.

In the valley to your left is Peacock Pond. The melting of Mills Glacier fills Chasm Lake, which feeds Columbine Falls and Roaring Fork, and ultimately fills Peacock Pond. The massive peaks of Longs Peak and Mt. Meeker form the backdrop of the scene.

Now, you get to enjoy a brief downhill walk and enjoy this awesome view.

In the late spring and early summer, you may have to hike across lingering patches of snow. It’s an easy walk along Roaring Fork before the final climb to Chasm Lake.

To get up to Chasm Lake, you will have to climb up a rock fall. There will be a few spots where you will do some rock scrambling, using your hands and feet. If you are unsure where to go, follow the rock cairns. Chasm Lake lies just on the opposite side of this short but steep and tiring climb.

Then, enjoy the views of Chasm Lake. Longs Peak is on the opposite side of the lake. To the right is Lady Washington and to the left is Mt. Meeker. We saw numerous rock climbers on Longs Peak the day we did this.

Tips to Have the Best Experience

Start the hike early, ideally by 7 am. During the summer months, afternoon thunderstorms are common, typically occurring by 2 pm. You need to be back in the tree line by 2 pm.

Do not expect your cell phone to work. For most of this hike we had zero cellular service. There were a few spots in clearings or at higher elevations where we got a few bars of LTE or 3G, just enough to send a text message. But don’t depend on your phone to call for help, talk to friends, or send photos to friends and family.

Be prepared to turn around early. If weather conditions change and you see approaching thunderstorms, be prepared to end your hike before you reach Chasm Lake. Your safety is more important than making it to the lake.

If you are not acclimated to the altitude, this is not a good first hike in Rocky Mountain National Park.The long distance, elevation gain, and altitude make this a tough hike. If you have not already spent time in Colorado adjusting to the altitude, I recommend that you spend a day or two acclimating to the higher elevation. Emerald Lake, Deer Mountain, and Gem Lake are good warm-up hikes.

If you plan to visit Rocky Mountain National Park from late spring through early fall, you will need a Timed Entry Permit for some areas of the park. Learn more here.

Get updates on trail conditionson the National Park Service website before you hike to Chasm Lake.

What to Bring on the Hike

Hiking shoes. Don’t do this hike in anything other than hiking shoes or hiking boots. There’s a good chance you will hike through snow, even in the summer.

Hiking poles. Hiking poles take the stress off of your legs and help to ease leg pain and fatigue.

Water and snacks. At least 3 liters of water in the summer.

Sunscreen, hat, and sunglasses. For more than half of this hike you will be exposed to the sun, with very little shade.

Camera. Even a smartphone will do. Chasm Lake is a great place to use the panorama feature.

Rain jacket or fleece. It’s chilly at Chasm Lake. Be prepared for all weather conditions, even snow in the summer months. Pack a rain jacket and/or fleece and even another layer of clothing.

If you have any questions about hiking to Chasm Lake, let us know in the comment section below. Happy hiking!!

More Information about Rocky Mountain National Park

ROCKY MOUNTAIN NATIONAL PARK ITINERARY: How many days do you need in RMNP? Get the answer to this question and learn how to plan your itinerary in our Rocky Mountain National Park Itinerary Planner.

BEST OF ROCKY MOUNTAIN NATIONAL PARK: For a list of top experiences, read our article Best Things to do in Rocky Mountain National Park. We also have a guide to the best hikes in Rocky Mountain National Park and how to spend one day in RMNP.

MORE GREAT HIKES IN RMNP: In our Rocky Mountain National Park Hiking Guide, learn about the top hikes to do in the park. We also have detailed guides on the Continental Divide Trail to Mt. Ida, Deer Mountain, Sky Pond, Gem Lake, and Emerald and Dream Lakes.

ESTES PARK: In our Guide to Estes Park, learn about where to stay, where to eat, and what to do.

NATIONAL PARKS BY SEASON: Rocky Mountain National Park appears in our Best National Parks to visit in February, June, September, and October articles. For more information about the best times to visit the national parks, check out our Best National Parks Month-by-Month Guide.