Obsidian Dome Rd, California, USA
Walk on a geological wonderClimbing atop a large hill of black glassy rocks, you might wonder if this is what walking on the moon feels like. The Obsidian Dome is a natural dome formed from solidified lava, part of the Mono-Inyo volcanic chain. Extremely hard and brittle, obsidian rock has been used for arrowheads and stone tools for hundreds of thousands of years, so wear strong footwear and be prepared for some sliding. You can drive to the base and hike up, and the trail can be skied or snowshoed in winter.