Wyoming is widely celebrated for its rugged peaks and expansive plains, but the state’s true geological complexity often lies hidden beneath the surface.
The Tongue River Cave System, nestled in the Bighorn National Forest near Sheridan, serves as a primary example of this accessible underground world. Spanning over a mile of navigable passages, the system features a subterranean stream and a natural waterfall. However, public access to this site is strictly regulated; visitors are required to obtain a permit before entry. This measure follows a history of vandalism that occurred, which ruined it for everyone else.
The Prehistoric Record at Natural Trap Cave
Not every site in Wyoming is open to the public. Natural Trap Cave, located at the base of the Bighorn Mountains near the Bighorn Reservoir, functions as a significant paleontological site. The cave is an 85-foot-deep limestone sinkhole that acted as a natural death trap for animals during the Ice Age. Researchers have recovered fossils from the bottom, including the remains of bears, cheetahs, lions, bison, and mammoths. The cave is currently closed to the public.
Explore the Massive Chamber Inside Wyoming Cave
For those interested in the sheer scale of Wyoming’s geology, the Great Expectations Cave in the Bighorn Mountains offers a stark contrast to smaller, more confined spaces. Situated at an elevation of 8,500 feet, the cave requires a climb before the descent into the earth. Once inside, visitors encounter the Great Hall, a massive chamber that spans 2,000 feet in length and reaches up to 100 feet in both width and height. It is one of Wyoming’s largest subterranean rooms.
The state’s caves are also linked to the history of the Old West. Near Kaycee, the Outlaw Cave provides a tangible connection to the Hole In The Wall Gang. The site is located near the Middlefork River, accessible via a hike from the Outlaw Cave Campground. This location was once used by Butch Cassidy, the Sundance Kid, and the Hole In The Wall Gang to stash their loot and hide from the law.
Similarly, Horsetheif Cave in the Bighorn Mountains derives its name from the horse rustlers and outlaws who utilized its complex, twisting passages to avoid the law. Unlike the more accessible sites, Horsetheif Cave is rugged, requiring climbing gear and caving experience to travel through its depths.
The diversity of these sites—ranging from the Darby Wind Caves near Alta to the fossil-heavy depths of the Bighorn range—reflects the state’s unique geological diversity. While some sites like the Darby Wind Caves remain popular, others serve as reminders that the most significant features of the Wyoming landscape are those that require the most protection.
Whether a site is open for permit-based exploration or closed to preserve a prehistoric archive, these caves remain an essential, if often unseen, component of Wyoming’s identity.
