Chasm Lake

Overview

A challenging hike to a pristine alpine lake beneath the dramatic east face of Longs Peak. The lake sits in a spectacular cirque surrounded by towering granite walls. The full route covers 8.4 miles round trip with about 2,360 feet of climbing, and most hikers finish it in around 6 hours. It sits in the Rocky Mountain National Park, near Estes Park in Larimer County, topping out at 11,760 feet.

Trail Highlights

How Hard Is It?

This is rated hard. The long 8.4-mile distance paired with demanding 2,360 feet of gain is what sets the effort level. You hike out to the turnaround and return the same way, so you see the route twice and can turn back early without missing the payoff. The high point is above 11,500 feet, where the thin air makes the climb feel harder than the numbers suggest. If you hike regularly, plan for roughly 6 hours of moving time; add a buffer for photos, snack stops, and the slower pace at altitude.

Best Time to Hike

The best seasons here are summer and fall. Summer is the reliable window once the snow clears, though that also means the busiest trailheads and the daily afternoon thunderstorm risk. In Colorado the weather turns fast in the high country, so start early, aim to be heading down by early afternoon, and watch the sky. Lightning, not distance, is what turns most summer hikes around.

Getting to the Trailhead

The trailhead is in the Rocky Mountain National Park, closest to Estes Park (Larimer County). You need a National Park entrance pass, and many park trailheads also require a timed-entry reservation in peak season. Check the park website before you drive out. The parking coordinates are 40.2621, -105.5968; plug those into your map app rather than the trail name, since several Colorado trailheads share names. Mountain weather and road closures can change access, so confirm the access road is open before a long drive.

Dogs & Kids

Dogs are not allowed on this trail, which is common inside national parks and sensitive alpine areas. It is a tough one for young kids given the 8.4 miles and 2,360 feet of gain. Save it for older, trail-tested kids or go without them.

What to Pack

Pack the Colorado basics: more water than you expect, layers for a 30-degree temperature swing, sun protection for the high-altitude UV, and rain protection for the afternoon. For a long, demanding hike like this one, the gear that earns its weight most is sturdy footwear and poles. Here is what we actually recommend for trails like this:

• ›hiking boots with real traction
• ›a packable rain shell
• ›trekking poles for the climb and descent
• ›a water filter for the longer day

Frequently Asked Questions