Devils Thumb Lake

Devils Thumb Lake is a high-alpine destination tucked beneath the imposing Devils Thumb rock formation in the Indian Peaks Wilderness of Boulder County. Sitting well above treeline in a dramatic glacial cirque, this lake rewards hikers with one of the most spectacular backcountry settings along Colorado's Continental Divide. The surrounding sub-alpine forest, towering rock walls, and the sheer face of Devils Thumb rising roughly 200 feet above the water create a landscape that earns this lake its perfect five-star rating from every visitor who makes the trek.

The hike to Devils Thumb Lake is a serious day commitment. From the Hessie Trailhead, the route runs about six miles one way with a moderate but sustained grade and a few notably steep sections. Most hikers pass Jasper Lake along the way, and the extra push from Jasper to Devils Thumb Lake is consistently described as worth every step. Pack light, bring plenty of water, and start early to give yourself enough daylight for the return trip. This is a long day on the trail, and the elevation gain demands respect.

What makes Devils Thumb Lake genuinely unusual among Colorado's alpine lakes is its hot spring feed. The geothermally warmed water makes this one of the only high-elevation lakes in the state where swimming is actually comfortable. Most alpine lakes in the Indian Peaks sit near freezing even in midsummer, so the chance to take a real swim at this altitude is rare and memorable.

Backcountry camping is available near the lake, but a permit is required. Campfires are not allowed, so plan on a camp stove for cooking. There are no restroom facilities. For hikers tackling the Indian Peaks southern loop, Devils Thumb Lake and nearby Jasper Lake are strategic overnight stops, particularly if you want to reach the Continental Divide Trail crossing early in the morning before afternoon weather rolls in. The pass above the lake narrows significantly and can feel exposed for those uncomfortable with heights, though bushes along the route offer handholds.

The area around Devils Thumb also attracts scramblers drawn to the Class 3 route from the lake up to the base of Devils Thumb itself. This is not a casual side trip and requires solid scrambling skills and comfort on loose rock. For most visitors, the lake itself is the destination, and the views from its shoreline deliver more than enough to justify the effort of getting there. Summer and early fall are the primary access window, as snow typically closes the trail from late October through June.