Why is water clear in a bathtub but look blue in a lake?

The water in a lake absorbs more red to yellow light wavelengths, reflecting blue to our eyes. Depth increases the effect.

Learn why murky water can kill >

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Posted: 16 July 2013
About the Author:

Alex di Giovanni has been editing The Torch since August 2006. Prior to joining the Smithsonian, she worked as a writer and editor for the National Geographic Society, Plexus Scientific, The Nature Conservancy, The National Foreign Language Center and St. Martin’s Press, among others. She has the best job in the world.