There's something counter-intuitive about calling a lake blue when every shade in this photograph is green! The lime-green algae of the lakebed almost jars with the softer green of the sunlit beech trees and the darker blue-shaded forest, but it just works as a colour scheme. The central star shape is the compositional feature that holds the image together.
Taken on Nikon F.4. 35mm lens, Kodachrome 64. Aperture F11