Mount Mazama (Giiwas in the Native American language Klamath) is a complex volcano in the state of Oregon, United States, in a segment of the Cascade Volcanic Arc and Cascade Range. Most of the mountain collapsed following a major eruption approximately 7,700 years ago. The volcano is in Klamath County, in the southern Cascades, north of the Oregon-California border. Its collapse formed a caldera that holds Crater Lake. The mountain is in Crater Lake National Park. Mount Mazama originally had an elevation of , but following its climactic eruption this was reduced to . Crater Lake is deep, the deepest freshwater body in the US and the second deepest in North America after Great Slave Lake in Canada.