A 320-acre swallow-hole of eroded badlands about an hour west of Casper, dropping suddenly out of flat sagebrush plains. Sandstone spires, deep gullies, and sulphur-stained ridges fill the bowl — striking from the rim, and once visited from below via a roadside tourist lodge that has since shut down.
The lodge is derelict, the gate is closed, and access is officially restricted, but the view from the highway pullout above the canyon is genuinely strange — and possibly enough on its own. The landscape doubled as the planet Klendathu in the 1997 film Starship Troopers.