Before Crater Lake came into existence, a cluster of volcanoes dominated the landscape. This cluster, called Mount Mazama (for the Portland, Oregon climbing club the Mazamas), was destroyed during an enormous explosive eruption 7,700 years ago. The eruption, estimated to have been 420 times more powerful than Mount St. Helens’ 1980 blast, reduced Mazama’s approximate 14,000-foot height by around a mile. So much molten rock was expelled that the summit area collapsed during the eruption to form a large volcanic depression, or caldera. Subsequent smaller eruptions occured as water began to filled the caldera to eventually form Crater Lake, the deepest lake in the United States.