Craters of the Moon, one of the most unusual landscapes in the country, was used to train NASA astronauts in 1969, features 1,100 square miles of lava fields and contains the deepest rift on earth. It's the perfect setting for the local celebration of International Obscura Day. More than 150 events take place in 39 states and 25 countries, commemorating the world's strangest places. AtlasObscura.com, a definitive guide to curious places worldwide, highlights miniature cities, books bound in human flesh, flaming holes in the ground, bone churches and Craters of the Moon.
Pathfinders can explore the otherworldly national monument on a guided cave walk. Space is limited to only 25. Participants need closed-toe shoes, a flashlight and a water bottle.