The deepest lake in the United States, formed almost 7,700 years after Mount Mazama collapsed. Driven totally by rain and snow, its breathtaking cobalt blue waters reach depths of 1,943 feet. The lake's remarkable blue hue comes from its enormous depth and purity; no entering stream exists to bring minerals or sediments. The strong light-absorbing action produced by the water's molecular structure and interactions with sunlight generates the vivid blue hue. The lake's purity has been maintained in part by its solitude above the Cascade Mountain Range. Unique thermal vents found on the lake's floor have been identified by scientists and help to create intricate underwater ecosystems. Rising to 2,000 feet above the lake's surface, the surrounding caldera walls guard the water from wind-driven mixing and assist to preserve its clarity. Native American oral histories entwine the formation narrative of the lake, therefore giving its scientific value cultural relevance. An invaluable source for research on climate change effects on alpine lake systems, regular monitoring of the chemistry and biology of the lake has revealed no changes over the previous century.
