Sunlight consists of the entire spectrum of electromagnetic radiation, which includes gamma, X, ultraviolet, visible, infrared, micro- and radio waves. The major part of solar radiation is in the form of visible and infrared rays that vary in wavelength. The transparency of water surfaces varies. The percentage of incident light reflected by a surface is called the albedo. The annual albedos of water bodies range from 5 to 7 percent at the Equator to 12 to 13 percent at 60 degrees latitude.
Light in the ocean is like light in no other place on Earth. It is a world that is visibly different from our familiar terrestrial world, and one that marine animals, plants, and microbes are adapted to in extraordinary ways. Light behaves very differently when it moves from air into water. It moves through the expansive depths of an ocean that is devoid of solid surfaces. These and other factors combine to create an environment that has no equivalent on land.
It's commonly believed that the ocean is blue because it's reflecting the blue sky. But this is a misconception. When sunlight hits the ocean, the water strongly absorbs long-wavelength colors at the red end of the light spectrum, as well as short-wavelength light, including violet and ultraviolet. The remaining light that we see is mostly made up of blue wavelengths.
Visible radiation, or light, from the Sun is important to the world's ocean systems for several reasons. It provides the energy necessary for ocean currents and wind-driven waves. Conversion of some of that energy into heat helps form the thin layer of warm water near the ocean's surface that supports the majority of marine life.