Direct light from the sun is called white light. It appears to have no color, however it is actually composed of all the colors in the spectrum. If you were to project it through a prism, you would see it break up into bands of color. Each color is a wavelength of light.
When we go underwater, water absorbs the wavelengths of light one by one as you get deeper.
- Red will disappear at a depth of around 15 to 20 feet.
- Orange at between 25 to 30 feet
- Yellow at 45 to 60 feet
- Green at 70 feet
- at 100 feet, everything will appear blue or grayish green
- at extreme depths all the light will be absorbed and everything will appear deep blue or black.
This explains why when I went diving and cut my hand at 25 meters … the blood appeared green !
Nugget of Knowledge 