The Color of Water

August 31, 2016

GreenSeaTurtleG0140322-4 (2)

Photographer: Cesar Cantu
Summary Authors: Cesar Cantu; Jim FosterAugust 2016 

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Have you ever noticed that the bluish tint of water is more obvious when viewed from beneath the surface? The blue color of water seen from above is often masked by clouds and reflected light from the sky and landscape (if near a coast). Water transmits light of all of the visible colors of the spectrum, but the blue and green colors are particularly transparent. According to Color and Light in Nature, water's peak transparency is near 480 nanometers (nm) -- between what we perceive as blue (about 475 nm) and what we perceive as green (about 510 nm).
Shown above is a green sea turtle (Chelonia mydas) that I observed in the shallow and noticeably blue waters off Xcaret, Mexico. Living mainly in tropical seas, it's named after the color of its skin and fat and not the color of its shell. Photo taken on August 15, 2016.

Photo Details: Camera Maker: GoPro; Camera Model: HERO4 Black; Focal Length: 3mm (35mm equivalent: 15mm); Aperture: ƒ/2.8; Exposure Time: 0.0006 s (1/1600); ISO equiv: 100; Software: Adobe Photoshop CS6 (Windows).