Spring Cave, in Colorado’s White River National Forest, is a large cave formed mainly by an underground river that still shapes it and carries what is described as the largest river flowing through a cave in Colorado. Reached by trail, the cave leads through rooms and chambers to the river, with further passages extending to an underground lake and submerged sections whose full extent remains unknown. Seasonal changes can sharply alter conditions, sometimes raising water to the entrance. Because white-nose syndrome has devastated bat populations, access is restricted to a limited season and requires registration and decontamination, reflecting the cave’s dual role as a recreation site and sensitive habitat.