The deepest lake (1,932ft) in the United States rests in a caldera, the circular crater of a collapsed volcano that once stood at 11 808ft. Spectacularly ringed by mountains that stay snow-covered most of the year, this crystal-clear sapphire lake, 6mi in diameter, attracts hikers and geologists. Rim Drive, which circles the lake, provides spectacular views, particularly at the Pinnacles, where 25m-high needle-like formations of rock, known as fossil fumeroles have formed.