Why So Blue?
27Mar,2025

Why So Blue?

BY : Rhiannon Nevinczenko

When we are little, we usually color two things blue: Water and the sky. Yet, the water in a glass is clearly...well, clear. So why is it when we look at the ocean and underwater photography, the scenes look like they were painted during an artist's blue period?
Color is a function of physics. White light, such as sunlight, contains all wavelengths of light (i.e., all colors). We perceive different colors as different objects absorb and reflect these wavelengths differently. When light hits water, the water itself acts similarly to a filter - absorbing some wavelengths and letting others pass through. As you go deeper down, fewer and fewer wavelengths have been able to get through. Red light is one of the first wavelengths to disappear because it is the longest wavelength. This is also why some deep sea animals are red pigmented - at the depth they live, there is no red light, making them appear black! Ultimately, most wavelengths are absorbed by the water itself, leaving mostly blue light behind for us to see.
Photo credit: Photo by Maël BALLAND via Pexels (Pexels license).

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