Water Is Actually Blue, Not Clear

While a single glass of water appears perfectly transparent, the vast blue expanse of an ocean or a deep lake tells a different story. It’s a common misconception that this color is solely a reflection of the sky. While the sky's reflection certainly contributes to the appearance of surface water, the true color is an intrinsic property of the H₂O molecule itself, a phenomenon explored by Nobel laureate C.V. Raman in the 1920s. This inherent color is simply too faint to be noticed in small quantities.

The subtle coloration is a result of how water molecules interact with light. The molecular bonds in water vibrate, and these vibrations are particularly effective at absorbing the longer, red wavelengths from the visible light spectrum. As white light from the sun passes through a significant volume of water, the red light is selectively filtered out. The remaining light that is scattered or transmitted back to our eyes is consequently enriched in the shorter blue and green wavelengths, giving pure, deep water its characteristic cyan or aquamarine tint. You can see this same effect in the brilliant blue color of dense glacial ice, which is simply a solid, highly pure mass of water.