The Sea Colors

“Why is the color of the sea blue?” Have you ever heard such a question? And perhaps some of the second grade students think, “Why is the color of the sea in Okinawa emerald green?” This time, though it is out of season, I'd like to answer these questions.
When the sun gets in the sea, the water absorbs red lights and reflects the blue lights. So, we feel the sea color is blue. This is the answer to the first question. However, the answer isn't only this. These days it is said that it's not true that the sea color is blue because the sea reflects the sky. But there is one theory which says that that is one factor for the sea appearing blue. According to the theory, we feel the sea color is blue in the sea because the sea absorbs red lights, but we feel the sea color is blue from out of the sea because the sea reflects the sky’s blue. Anyway, the particular machinery of this is not certain.
Then, why is the sea color not only blue? Why are the colors of the sea in Okinawa or other beautiful seas emerald green? This is because the sunlight hits not only water. For example, when the sunlight hits the plankton, the plankton absorb red lights and blue lights, and put out the orange lights or green lights. So, if there is lots of plankton, the sea looks green-brown. The sea in Tokyo has a lot of plankton, so the sea looks brown and doesn't look transparent. The sea in Okinawa and other beautiful seas have little plankton, so the sea is clear. And in the shallow part of the sea there, white sand reflects the sun light, so the sea looks emerald green.

There are various colors in the sea. It depends on the depth, the number of plankton, and whether we are in or out of the sea. These colors seem to express the condition of the sea. Which sea colors do you like?

116-3 Nanami Miura