On the crest of the southern Cascade range, at an altitude of 6,164 feet (1,879 m), Crater Lake is in a crater of the ancient volcano Mt. Mazama. It has no inlet nor outlet. Its water level is maintained (as it was created) by precipitation. The lake is six miles (10 km) in diameter. Its greatest depth is 1,932 feet (589 m). It originally was known as Deep Blue Lake because of its color in sunlight. Prospectors discovered Crater Lake in 1853. In 1902 the lake and a surrounding area of about 160,000 acres were designated Crater Lake National Park.