We often try to hit the beach to enjoy the sandy beach and also to appreciate the beauty of the blue ocean. Some of us go a step further and hop on a cruise or sail to enjoy the blueness even closer. Why is the ocean blue in color? It is in fact water and should be colorless right!! Is it because the water reflects the blue sky and hence is of the same shade as the sky?

The above explanation may sound sensible to some but it is not even close to the real reason as to why the sea is blue in color. The real reason is that the water is a very good absorber of the long wavelength light. As you know the spectrum of light contains longer wavelength colors which are the red, orange and yellow as well as shorter wavelength light blue. While the red, yellow and orange colors are absorbed by the water, it reflects back the blue color thereby giving it blue color.

But at this juncture one might ask why do certain sections of sea especially by the beach bear lighter shade of blue or green as its color than the deeper counterparts.

art of the answer is, deeper the sea the more light it will be able to absorb. Thus the deeper sections of the sea end up absorbing the longer wavelengths better thereby appearing dark blue. However, that does not answer why certain beaches have water that are slightly greenish in shade. This has got more to do with the growth of minute organisms called phytoplankton. The phytoplankton are plant like organisms that absorb sunlight with the help of chlorophyll and produce energy. The chlorophyll essentially gives the green color to the water. The more phytoplankton in the region the greener the water. Hope this clarifies your doubt on the ocean’s color completely.

However recently a study has concluded that the ocean will turn bluer by the end of century mainly due to the loss of phytoplankton as a result of global warming. To know more about this read the following article : The Color of the Ocean is changing