The most striking feature of Crater Lake is its color. So, why so blue? The answer has to do with physics and how light is absorbed as it passes through the crystal clear water. The first colors to be absorbed are reds then the yellows, and last are the shades of blue. Only the deepest blue returns to the surface to be seen by the human eye. I would imagine most visitors will be like those deep blues and want to return again to this scenic gem.