Pinnacle Valley's sprires are formed by dormant and cooled volcanic fumorals which retain hollow cores while cooling. This viewpoint is just outside the south park entrance on Highway 60. Crater Lake, the most famous feature of Crater Lake National Park spans five miles and is ringed by nearly 2,000 foot cliffs formed by the collapse of a volcano called Mount Mazama. The 1,943 foot lake is the deepest lake in the U.S. and one of the deepest in the world. Crater Lake National Park, in Oregon, is a highlight of the National Volcanic Scenic Byway.