| |

What You Need to Know Before Hiking to Chasm Lake – Rocky Mountain National Park’s Most Magnificent Alpine Lake

Sarah and Tim stand at Chasm Lake at the base of Longs Peak in Rocky Mountain National Park
Chasm Lake at the base of Longs Peak in Rocky Mountain National Park

Chasm Lake is our new favorite hike in Rocky Mountain National Park. This stunning alpine lake sits directly beneath Longs Peak, one of Colorado’s iconic 14ers at 14,259 feet and the tallest mountain in all of RMNP. The hike ascends through the forest and beyond the tree line before the trail meanders across the tundra to an idyllic valley view of waterfalls, lakes, and wildflowers (in summer). And that’s all before you even get to Chasm Lake.

The Chasm Lake hike is a great option for experienced hikers who want an approachable challenge. The trailhead is only an hour and a half from Denver, Colorado, so it’s a great day-hike option from the city!

In this guide, we share everything you need to know for a safe and rewarding hike to Chasm Lake, from finding parking to detailed descriptions of each portion of the trail. We’ll also show you the view from what may just be the world’s most scenic drop toilet!

Chasm Hike trail info, distance, elevation gain, difficult rating

Chasm Lake Hike Trail Basics

Chasm Lake Hiking Trail
First views of the mountains on Chasm Lake Hiking Trail

How long is the hike to Chasm Lake?

The hike to Chasm Lake is 8.8 miles round-trip with 2,542 feet of elevation gain. The hike starts at 9,218 feet above sea level and ends at 11,760 feet above sea level. It takes an average of 5.5 hours to complete. It took us longer, mostly because we stop for photos a lot and spent a lot of time relaxing at the lake, enjoying lunch, the sun shining, and the views of Longs Peak towering above us.

Overall, the hike to Chasm Lake is challenging and we only recommend it for experienced hikers. For a milder hike with awesome alpine lakes, we recommend the Emerald Lake trail which features four different alpine lakes! Our blog post on the Emerald Lake hike has everything you need to know. Plus, it’s kid-friendly!

Chasm Lake
Chasm Lake and Longs Peak

A note on altitude sickness in Colorado

If you are visiting Colorado from a lower-elevation location, you will likely feel some of the effects of high altitude, including shortness of breath, headaches, dizziness, and fatigue. We recommend spending a few days acclimating in Denver before attempting a strenuous mountain hike. While altitude sickness impacts everyone differently, the best way to prevent it or alleviate symptoms is to make sure you are staying very well hydrated. We always hike with electrolyte powders like DripDrop or Liquid IV.

Where is the trailhead for Chasm Lake?

The trailhead for Chasm Lake is located in the Longs Peak Area of Rocky Mountain National Park. This is outside of the main area of the park, 11 miles south of Estes Park. You do not drive through an official park entrance station to get to the Chasm Lake trailhead but should still plan on paying for entrance and obtaining a timed entry permit (more details on the timed entry permit below).

Chasm Lake shares a trailhead with the summit trail to Longs Peak. The parking lot is frequently full by 3 A.M. (Yes, you read that right). People attempting to summit Longs Peak have to begin their descent prior to noon when afternoon thunderstorms roll in during the summer and hikers above tree line are exposed to lightning risk.

If the parking lot is full when you arrive, you will need to park on the road outside of the national park boundaries. We had to walk about a half mile to the trailhead from where we parked just beyond the sign for the Longs Peak Area of Rocky Mountain National Park. Do not try to park on the street past that sign. Street parking within this part of the national park is not allowed and you may return to your car to find a parking ticket!

Do I need a timed-entry permit for Rocky Mountain National Park to hike Chasm Lake?

If you are planning to hike Chasm Lake during the non-winter months (which we’d recommend for this trail), technically you do need a timed-entry permit between 9 AM and 2 PM, in addition to park entrance admission or National Parks pass (such as the America the Beautiful Pass linked in the first blue box below). While there isn’t an official entrance station outside of the trailhead, there is a ranger station, and park rangers may stop you to validate you have a permit between 9 AM and 3 PM.

Dates vary year to year but are usually May through October. Check the official national park page for the most up-to-date information.

How does Chasm Lake compare to Sky Pond?

Chasm Lake and Sky Pond are both challenging alpine lake hikes suited for experienced hikers. We think, subjectively, Chasm Lake is slightly easier than Sky Pond, which surprised us since the elevation gain is greater and the distance is only a half mile shorter for Chasm Lake than for Sky Pond. Sky Pond is 9.4 miles long round trip, with 1,758 feet of elevation gain. To read more about the Sky Pond hike check out our blog post for all the details!

Are dogs allowed?

Dogs are not allowed on any trails within Rocky Mountain National Park. Plan to keep your pups at home, or, if you must bring your dog to the park, please know they will be limited to picnic areas and parking lots and must be leashed whenever they aren’t in the car.

Chasm Lake Trail Description


The trail starts at the Longs Peak Ranger Station, where you will immediately start a steady ascent through lodgepole pine, spruce, and fir trees. This part of the trail is shady and pleasant, albeit steep! Along this part of the trail, you’ll pass a junction for another trail (Eugenia Mine Trail) after about a half mile. Stay on your current path. Eventually, about 1.2 miles from the trailhead, you will pass a wooden sign for the Goblins Forest Backcountry Campground. 

From here, it’s another mile of the forest before you emerge above the treeline! Look for the twisty, mangled trees common to this transition zone between where trees can and cannot live. It’s a fascinating visual depiction of the impact of the decreased oxygen levels at this altitude (which, at this part of the trail, is about 11,000 feet above sea level).


When you no longer see the gnarly trees, you’ll have entered the tundra portion of the hike. This is also where you’ll get your first views of Mount Meeker, Longs Peak, and Mount Lady Washington. Look out for marmots and ground squirrels who frequently scuttle about this stretch of the hike. 

Peacock Pool and Columbine Falls Rocky Mountain National Park
Peacock Pool and Columbine Falls

Approximately 3.5 miles from the trailhead, you’ll arrive at the Chasm Lake Trail junction. This next part of the trail is, in our opinion, the prettiest stretch of the hike before you reach your destination. It’s a moderate incline along the wall of a gorge with stunning valley views. Take your time on this part of the trail and be sure to look in all directions for spectacular mountain scenery, lakes, and waterfalls. To your left, as you ascend, look down to the valley to see Peacock Pool and Columbine Falls. In the summer, you’ll see patches of the falls’ namesake purple flower.  

Final Ascent to Chasm Lake

At the base of the rock scramble, there is an outhouse with incredible views of Longs Peak. It may just be the most scenic toilet in the world, but we’ll leave it to you to decide! 

This last stretch of the hike is the most technical, requiring a bit of wayfinding and rock scrambling, though it’s not technically “technical” and the rock scrambling isn’t as steep as it first appears. 

Tim on the rock scramble to Chasm Lake
The final ascent to Chasm Lake is a rock scramble

At the top of the rocks, you will get your first view of Chasm Lake! Congratulations! Chasm Lake sits at the base of Mount Lady Washington and Longs Peak. This east-facing wall of Longs Peak is known as the “Diamond” and rises dramatically 2,400 feet above Chasm Lake. You’ve made it! Enjoy the views and relax a bit. We always recommend a scenic sandwich (or in our case, usually a bagel!) at your hiking destination. 

Note: It’s important to begin descending back to the Chasm Lake trailhead prior to noon. Rocky Mountain National Park consistently gets afternoon thunderstorms in the summer, and it’s unsafe to linger above the treeline where lightning strikes are common. 

What to Pack to Hike Chasm Lake

  1. Day Pack: Because this is a longer hike, it’s so important to have a good day pack to carry everything you need. I’ve had the Osprey Skimmer 20 for Women for years and it’s held up on every adventure! And here’s the Osprey Talon 22 Pack for Men!
  2. Water Reservoir: If your day pack doesn’t have a water reservoir in it already, you can buy one separately to slip into your bag. These are so important for staying hydrated and comfortably carrying several liters of water with you for longer hikes! Here are our favorite 2-liter reservoir and 3-liter reservoir!
  3. Sun Protection: This is so important no matter the season! Sun Bum is our favorite sunscreen brand.
  4. Hiking Boots: I hiked to Chasm Lake in my Columbia hiking boots. You can’t beat the price for the quality, too. Tim wore his Foxelli boots and swears they are the best hiking boots he’s ever owned.
  5. Socks: I started wearing these double-layer Wrightsock brand socks when marathon training years ago and have never gotten a blister with them! The hike to Chasm Lake covers rocky terrain, so it’s nice to have blister protection! In winter, I might mix it up with merino wool socks, too.
  6. Sunglasses: I love these wooden frame sunglasses, so they are my go-to.
  7. Hiking pants: These hiking leggings are my favorite in winter. In summer, I usually hike in biker shorts or leggings.
  8. Moisture-wicking layers: SmartWool is our favorite layering brand. I wear this pullover all the time and their wool t-shirts are great base layers. There are also SmartWool t-shirts for men!
  9. Jacket: Because of the high elevation of this hike, even in summer it can be really chilly at Chasm Lake! I always pack my Columbia jacket when hiking in the mountains.
  10. First Aid Kit: An ultralight first aid kit is a must-have for every hike, but especially challenging ones like this where it’s even more important to be prepared in case of injury.
  11. Camera: I always hike with my Sony a7iii. It’s a great full-frame camera for capturing all of our hiking memories!
  12. Snacks: Clif Energy Bars are our favorite hiking snack, for a good mix of carbs, fats, and protein to power us through our hikes!
  13. Trekking poles: Many people like hiking with trekking poles to offset the burden on the knees, especially going downhill. We don’t use ours often, but these Black Diamond Trail Back hiking poles are really popular!

Guided Tours in Rocky Mountain National Park

Looking for a guided experience in Rocky Mountain National Park? Check out some of these tours you can book to help you make the most of your time in RMNP without the hassle.

Where to Stay in Estes Park

We recommend basing yourself in Estes Park when visiting Rocky Mountain National Park. Here are some well-rated hotel options in Estes Park, which is just a few miles from the Beaver Meadows entrance station to RMNP.




Click here to search for additional hotels in Estes Park or search below!


Final Thoughts on Chasm Lake

Chasm Lake is one of the most scenic hikes in Rocky Mountain National Park. Nowhere else can you stand beneath towering Longs Peak in a deep cirque surrounded by some of Rocky Mountain’s most breathtaking peaks. 

If alpine lakes are your jam like they are for us, don’t miss Sky Pond or Emerald Lake hikes! With a few days in RMNP, you could hike all three, and even add on a scenic drive on Trail Ridge Road, the highest continuous paved road in the United States!

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *