The science behind the ocean color appears blue primarily because of the way sunlight interacts with water molecules.
Here’s why:
1. Selective Absorption and Scattering of Light
- Absorption: Water absorbs colors in the red, orange, yellow, and green spectrum of sunlight more effectively than blue. As sunlight penetrates the water, the red, orange, and yellow wavelengths are absorbed quickly, leaving mostly blue light.
- Scattering: Blue light is scattered by the water molecules more than other colors, which is why we see the ocean as blue.
2. Depth Matters
- In shallow areas, the ocean may look green, brown, or turquoise because of light reflecting off the seafloor or particles in the water, like algae or sediment. In deeper parts, where there’s less influence from the surroundings, the blue effect is more pronounced.
3. Sky Reflection (Minor Contribution)
- While the ocean can reflect the color of the sky, this is a secondary factor. The blue you see mostly comes from the inherent properties of water itself.
Fun Fact:
If you are an advanced scuba diver and were to dive deep into the ocean, the red and yellow parts of the spectrum fade away as you descend. This is why underwater objects can look blue or green at depth unless illuminated by artificial light.
“The ocean acts like a sunlight filter.”from NOAA