Three Island Lake

Managing agency

Arapaho-Roosevelt NF — Boulder RD

Three Island Lake is an 11.4-mile out-and-back trail located in Colorado near the Boulder Ranger District of Arapaho-Roosevelt National Forest. The hike gains 2,410 feet of elevation, making it a moderately challenging day trip for hikers seeking alpine scenery. The trail is managed by the Arapaho-Roosevelt National Forest, Boulder Ranger District, ensuring maintained conditions and proper trail stewardship. This out-and-back route allows hikers to turn back at any point, offering flexibility for various fitness levels. The elevation gain of 2,410 feet is distributed across the 11.4-mile distance, providing a steady climb toward the destination. Hikers should prepare for high-altitude conditions and bring adequate water and supplies for the full roundtrip journey. Three Island Lake serves as the turnaround point for this hike, rewarding hikers with alpine lake views after ascending through forest and potentially above treeline terrain. The out-and-back format means hikers cover the same terrain on the return descent, allowing for a familiar route back to the trailhead.