Fern Cave National Wildlife Refuge is a 199-acre protected area near Paint Rock in northeastern Alabama, set on the western side of Nat Mountain above the Paint Rock River valley. Its importance lies in safeguarding Fern Cave, a deep and extensive maze of passages and canyons that contains rare species and fragile habitats. The cave once held a significant population of federally endangered American hart's-tongue ferns, later sharply reduced by illegal collecting after 1985. It also supports the largest colony of federally endangered gray bats in the United States, with more than 1.5 million using it annually. Because of these sensitive resources, the refuge is undeveloped and closed to general public access.