Crater Lake Caldera, Oregon, with Wizard Island Cinder Cone -- From a probable altitude of roughly 12,000 feet, the top of former Mount Mazama was lost to eruption and collapse that left the present huge crater and the deepest lake ( Crater Lake - 1,932 feet) in North America. Explosive eruptions built Wizard Island (at least 800-900 years ago) and two other cones (submerged) on present crater floor. From: Foxworthy and Hill, 1982, Volcanic Eruptions of 1980 at Mount St. Helens, The First 100 Days: USGS Professional Paper 1249