Crater Lake, a deep lake within a huge volcanic caldera in the Cascade Range, southwestern Oregon, U.S. The crater, 6 mi (10 km) in diameter, is the remnant of a mountain, Mt. Mazama, which rose much higher (probably to 12,000 ft [3,650 m]) until an eruption more than 6,000 years ago destroyed the upper portion. Later, lesser outbreaks are indicated by cinder cones on the caldera floor; one of these, Wizard Island, rises above the water. The intensely blue lake, which is 1,932 ft deep, and its surrounding region became a national park in 1902, which includes 250 sq mi (647 sq km).