A record clarity reading of 142 feet was recorded by scientists at Oregon’s Crater Lake on June 25, 1997.

The deepest lake in the nation is the star of Oregon’s only National Park. It is fed exclusively with melted snow and rain water and is famously clear and blue:

The water is so blue because there is hardly anything else in it – just water. It’s not pure water, but it’s close. We’ve all seen the colors in a rainbow when normal white light passes through a raindrop and breaks into the individual colors of the spectrum. All those colors are in sunlight. The reason different objects appear to be different colors lies in the molecular structure of the chemicals that make up that object. For example, a red shirt appears red because the chemicals in the fabric dye are put together in a way that absorbs all of the colors except red. The red wavelengths then bounce back, hit our retina, and our brain sees “red.” Water molecules, just plain water with no sediments, algae, pesticides or pollution, will absorb all the colors of the spectrum except the blues. Those wavelengths will bounce back and make the water appear blue. The key is to have relatively pure water and lots of it. There has to be enough molecules to absorb all the other colors. (There are 4.6 trillion gallons of water in the lake, so it works really well.)