Why is the ocean blue

There are a number of different theories as to why the ocean is blue ranging anywhere from it being the reflection of the sky at a particular time to the presence of various matter floating about in the water. The most prominent theory supported by scientific fact, however, lies in the refraction of light waves generated by the ocean’s deep water.

Due to the fact that our perception of color is, in fact, merely a perception of various light wavelengths being received by our visual receptors (i.e. our eyes) and translated into a color perception by our brains whatever wavelengths are let off by the ocean must be those that are not absorbed. Being able to store many of the red spectrums generated by sunlight and refract blue wavelengths in various directions this is thought to be one of the primary factors in the
ocean appearing blue in many cases – particularly in deep areas where non-blue wavelengths can be absorbed more effectively.

Many times if the ocean does not appear blue (as it appears green in many coastal areas) this is thought to be the result of other matter present within the water. Green algae, for instance, absorbs more energy and in turn refracts yellow wavelengths that mix with the blue in order to create a more greenish hue, thus causing us to perceive the water as an off-blue tint.

Other brownish colors can also be seen in the water surrounding many areas either in river deltas or following storms in particular. These are generally the result of various debris being mixed with the water due to flow disturbances to create an off-blue look and if cleared will generally result in a much more vibrant blue color being refracted.

More shallow areas of the ocean will also typically result in a less blue appearance due to the fact that less water is available to absorb the various other light wavelengths and reflect the blue back to an observer. This can result in a number of different color combinations being generated depending on the depth of the water as well as the present of other matter in it that may affect the overall color (such as high iron levels even turning water red).