Eagle Cave, near Blue River, Wisconsin, is the state’s largest onyx cave and the first in Wisconsin to be commercially owned and operated. Discovered in 1849 and opened to the public in 1938, it developed from a natural feature into a visitor attraction. It also became a notable camping destination, especially in fall, winter, and spring. Since 1954, its long-running cave exploratory program has given it a distinctive role, allowing youth groups to camp inside the cave and participate in organized underground recreation and group activities.