Chasm Lake

Chasm Lake is a high-alpine lake tucked beneath Longs Peak’s east face in a steep glacial basin. It’s a destination for a serious day hike, not a quick pull-off: the route from Longs Peak Ranger Station is 4.2 miles each way with 2,360 feet of climbing, starting around 9,300 feet. Plan for about 8.4 miles round trip at altitude. If you want the lake framed by Longs Peak’s huge granite wall, this is one of the park’s strongest hike payoffs. If you’re short on time or looking for an easy lake walk, choose another stop.

The trail starts in forest, climbs through a band of stunted trees near treeline, then reaches exposed tundra. Along the way you pass Columbine Falls and Peacock Pool, a pool below the gorge. From Chasm Meadow, the route turns toward the lake and climbs through a gap in the rocks. A short, rough scramble over the headwall hides the water until you’re almost there. Some shore viewpoints also involve scrambling over boulders. Snow can linger on a steep stretch before Chasm Meadow into mid-July in a typical year, though timing changes with conditions.

At the lake, the Diamond, Longs Peak’s steep east face, rises nearly 2,400 feet above the water. Mount Lady Washington frames the view to the north and Mount Meeker to the south. You can also see the Keyboard of the Winds. For the classic photo, keep the lake in the foreground and fit the Diamond above it. A shoreline boulder adds scale. Some angles mean scrambling, so use only a safe route to the rocks.

Mills Glacier carved the basin known as The Chasm, tearing rock from Longs Peak’s east face and carrying it downhill. As the ice retreated, it left the bare rock walls, fine grit between the boulders, and long moraine ridges in the valley. The steep bowl around the lake is the glacier’s work on a scale you can read from the shore.

The Longs Peak trailhead serves both this hike and climbers headed for the summit, and its parking lot can fill before dawn. Plan an early start rather than counting on an open space later in the morning. Carry food and enough water for the full hike; there’s no food service at the lake. Vault toilets are at the trailhead, and hikers report a privy near Chasm Junction, several miles before the lake. Pets aren’t allowed on park trails, tundra, or meadows.