The Mount Massive Wilderness is a federally designated wilderness area in the Sawatch Range, located in the U.S. state of Colorado. It is operated jointly by the United States Forest Service and the Fish and Wildlife Service as part of the San Isabel National Forest and the Leadville National Fish Hatchery. It is 30,540 acres (123.6 km2) in size, with 27,980 acres (113.2 km2) in San Isabel National Forest and 2,560 acres (10.4 km2) in Leadville National Fish Hatchery, and it was designated by the US Congress in 1980. The name comes from Mount Massive, the second highest peak in Colorado, located inside the wilderness. Elevations in the wilderness range from 9,700 feet (3,000 m) to 14,421 feet (4,396 m). It is the only federally designated wilderness area within the National Fish Hatchery System.