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  • Writer's pictureVien R. Guenther

Hiking to Chasm Lake, Estes Cone and Twin Sisters Peak - Rocky Mountain National Park

Updated: Jul 30, 2020

Rocky Mountain National Park encompasses a big area, about 265,461 acres (414.78 square miles). There are four National Forest lands surrounding the park - Roosevelt National Forest to the north and east, Routt National Forest to the north and west, Arapaho National Forest to the west and south, and Indian Peaks Wilderness located south of the park. When the park was first established in 1915, there were one hundred miles of trails already existing, but in later years, new trails were added. Some of these trailheads are located outside of the main park, but the trails are still within the park, which you can hike without paying the entrance fee.

There are several trails that we regularly hike which start outside of the main park. Three of these trails are located between the towns of Allenspark and Estes Park – Chasm Lake, Estes Cone and Twin Sisters Peak. These trails are within short distances from each other, so it is best to stay one or two nights in the area if you want to hike all three, or come back another day.


The Longs Peak trail attracted tourists since the 1860’s, especially climbers aiming to reach the prominent and iconic fourteener, Longs Peak, one of the best known summits in the Rocky Mountains. This trail is where Enos Mills became skilled as a naturalist, which made him the most vocal advocate for the creation of Rocky Mountain National Park. This trailhead is shared between climbers wanting to summit Longs Peak, as well as hikers whose aim is just to reach Chasm Lake. This trailhead is also one option for the hike to Estes Cone.

To get to the trailhead from Highway 7 heading north, about six miles from the town of Allenspark, turn left to Longs Peak Road. It will take you to the trailhead. This is a very popular trail so you have to be real early to get a parking spot. Climbers who want to do Longs Peak usually arrive here in the middle of the night, between 3 to 5 a.m. Well, if you are hiking to Chasm Lake you don't have to be that early.

Longs Peak. Panorama photo by Hermann Guenther

CHASM LAKE – 8.4 miles round trip (via East Longs Peak Trailhead)

There are several trails you can take to Chasm Lake, but when you are in the main area of the park and want to follow the North Longs Peak Trail, the hike is long and arduous. The most direct trail is from East Longs Peak Trailhead. This hike is not a "walk in the park" either, it starts from moderate and get strenuous as you go up higher, but at least it is shorter. You will cross several streams on some log bridges.

A little over two miles from the trailhead you will emerge from the forest and the view opens up - you entered the subalpine zone, a transition zone between forest and tundra. The landscape along this stretch of trail is called krummholz, a German word that means twisted wood. You will notice the trees here are stunted and irregular.

Above timber line with Twin Sisters Peak behind
Mount Meeker, Longs Peak & Mount Lady Washington

We hiked here in autumn, when the shrubs have changed their color from green to rusty, yellow and golden. See photo below, the colors are gorgeous aren't they? The weather is a little cooler as well in autumn, which is an ideal time for hiking in an open landscape - the sun can be very fierce in summer. On this stretch of the trail you will see the mountain landscape and the three prominent peaks - Mt. Meeker, Longs Peak and Mt. Lady Washington.

Heading on the trail below Mt. Lady Washington

The trail continues along the base of Mt. Lady Washington on the left, but before that there is a turn-off to the Keyhole Route which is a non-technical route to Longs Peak - except in winter time. The trail below Mt. Lady Washington becomes slightly challenging due to the scree, or small loose stones along the trail. This scree is like pebbles when you step on it, so it's good to have hiking poles.

Below Mt. Lady Washington is Peacock Pool and not far ahead is Chasm Lake. Before the ascent to the lake you might want to answer "nature's call". Off the trail, just below the last ascent to Chasm Lake, you will find a loo or an outhouse. There is no roof but don’t worry, no one will see you from above.

Scree along the trail below Mt. Lady Washington
Peacock Pool below the trail
The loo with a view

From the loo, just a little uphill and you will reach Chasm Lake (11, 825 feet), tucked below the base of Longs Peak (14,255 feet) on the west side, Mount Lady Washington (13,281 feet) on the north side and Mount Meeker (13,911 feet) on the south side.

Chasm Lake and the "Diamond" face of Longs Peak
Chasm Lake

Looking up from the lake you will realize the scale of Longs Peak. Its nearly vertical “diamond” face is what climbers aim for to reach the peak. Look up you might see some of them.

Chasm Lake

Hiking back from Chasm Lake you will probably wonder what are those mountains ahead in front of you. On the left is Estes Cone and on to the right is Twin Sisters Peak, two hikes that you might want to take, if you haven't yet. The views from those two peaks are fantastic.

Trail with a beautiful mountain view - Estes Cone on the left and Twin Sisters on the right


To get to the Twin Sisters Trailhead from Highway 7 heading north, it is about 8.6 miles from the town of Allenspark - about 2.5 miles from the Longs Peak trail turn-off. From the highway you have several choices where you want to begin your hike. You can park either at Lily Lake Trail and begin your hike there, or park on the east side across the road from Lily Lake. To make your hike a little shorter, you can drive up on a rough road past the parking lot for about half a mile to the main trailhead. There is no designated parking but you can park on the side of the road. You have to be early to get the spots nearest to the trail.

TWIN SISTERS PEAK – 7.0 miles round-trip

This is one of our favorite trails outside of the main park. It is also a moderate to strenuous hike. Part of this trail has changed after the storm of September 2013, resulting in a big landslide (you will see the scar from the highway) washing out part of the trail. The trail has a number of switchbacks after you cross over the slide area at one point.

At the beginning of the trail you will also traverse into thick forest, but as the forest begins to thin out the view will open up and you will see Longs Peak, Mt. Meeker, Powell Peak, Taylor Peak, Lily Mountain and Estes Cone.

You will not notice it, but the trail actually enters and exits Roosevelt National Forest several times. So only part of this trail is in Rocky Mountain National Park property.

Bighorn Sheep
A rugged terrain trail

Above tree line, the trail will traverse some rugged terrain. Keep your eyes open and look around you, you might find some Bighorn Sheep. We did and it was really cool seeing a bunch of male bighorns up close. But don't get too close - you might get "rammed".

To the summit
That was a windy day
Enjoying the view from the summit

It can get windy and chilly above tree line, so bring along your jacket. Before the last ascent to the summit, you will find a stone building and a radio communications tower, used for locating lost hunters and downed aircraft.

Traversing the rugged ridge of Twin Sisters Peak
The rugged summit

At the summit is an exceptional 360-degree panoramic view of Mt. Meeker, Longs Peak, Mt. Lady Washington, Estes Cone and the Continental Divide, as well as the Great Plains to the east.

View of Mt. Meeker and Longs Peak from Twin Sisters Peak

ESTES CONE (via East Longs Peak Trail - 6.5 miles round trip, from Lily Lake via Storm Pass Trail- 7.5 miles round-trip).

Driving on Highway 7 toward Estes Park, you will see this cone-shaped mountain of Estes Cone. It looks like a volcano but its shape is actually due to natural erosion. It's not conical all around though, just from the highway on the south side.

Estes Cone from Highway 7, looking north

Hiking to Estes Cone starts either at East Longs Peak Trailhead or at the Lily Lake Trailhead - both trails are a moderate to strenuous hike. From the East Longs Peak trail is a junction to the Estes Cone Trail, less than a mile from the trailhead.

Lily Lake with Estes Cone (right) & Mount Meeker & Longs Peak in the back
Wildflowers by the trail

We mostly begin our hike from the Lily Lake Trailhead following the Storm Pass Trail. This trail is a mile longer than going via the East Longs Peak trail but you get to see a little view and wildflowers along the way.

View from Storm Pass Trail

The hike is mostly uphill on either trail but the steepest part begins at the Storm Pass Trail junction where both trails meet. Hikers use this junction to rest or have some snacks to boost their energy for the steepest ascent on this hike.

The trail has switchbacks on rocky outcroppings - it’s an ankle breaker and hiking boots are useful in this kind of terrain. The last stretch is a little scrambling on rocks to the top. We leave our hiking poles behind here since you will need hands and feet to reach the top (as well as your butt climbing down).

The last ascent to the top
Scrambling on rocks
View of Longs Peak behind

At the summit of Estes Cone (11,006 feet), you will see an incredible 360-degree view of the surrounding mountains - Lily Mountain, Twin Sisters, Mount Meeker and Longs Peak. You can spend a while up there looking at the beautiful landscape but you have to be mindful of the afternoon thunderstorms as you will be exposed up there.

Estes Cone summit with the view of Twin Sisters Peak

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