Crater Lake (in southern Oregon, in the United States) is “freshwater” in the extreme. It’s one of the purest natural bodies of water on our planet. It’s pure enough to safely drink it directly, without having to filter it first.
Crater Lake, Oregon, USA is a freshwater lake. It was formed when a volcanic caldera filled with water. Water inputs are from direct precipitation. It has no inflow or outflow streams like many other 'normal' lakes and is one of the clearest lakes in the world.
