Obsidian Dome is accessible via a 2.7 mile dirt road. Head north on US-395 towards Lee Vining and Mono Lake. Turn left onto Obsidian Dome road for 0.3 miles. Continue onto Glass Flow Road for 0.6 miles. Continue left onto Obsidian Dome Road at Obsidian Flow and Hartley Springs Campground turnoff. From here you will drive around the dome to its south side. After 0.6 miles, turn slightly left at 2S10. Continue onto Glass Creek Rd. At the fork in the road, stay to the left to park near Obsidian Flow among the large Jeffrey pines.