The lake partly fills a 2,148-foot-deep (655 m) caldera that was formed around 7,700 (± 150) years ago by the collapse of the volcano Mount Mazama. No rivers flow into or out of the lake; the evaporation is compensated for by rain and snowfall at a rate such that the total amount of water is replaced every 250 years.
Is it safe to drink Crater Lake water?
Why doesn't the park just use the water in Crater Lake? Consuming Crater Lake water would conflict with the park's mission to preserve the lake. The park's water claim for the lake is for the preservation and protection of all natural habitats and the conservation of scenery. It is not for human consumption.
Has anyone swam across Crater Lake?
In 1929, Lee Fourrier became the first person to swim across Crater Lake, but her swim was only one way. More recently, serious swimmers ride out to Wizard Island on one of the tour boats and swim to the dock, as the boat dock is the only legal access to the water from the rim.