Why is the Ocean Blue?

Written By:  Andrew Eide

The poem IN 1492 goes:  “In fourteen hundred ninety-two Columbus sailed the ocean blue.” The Earth has been called the Big Blue Marble as that is how it appears from space. The oceans have been called the deep blue seas, along with other references to the water being blue.

So the first question which pops into my mind is why all these references to the waters being blue when water is clear?

I did a little research and I found the following theories:

Blue wavelengths are absorbed the least by the deep ocean water and they are scattered and reflected back to the observer’s eyes.

Particles in the water may help to reflect blue light.

The ocean reflects the blue sky.

My research also came up with the following information:

The ocean usually appears blue to us because this is the color our eyes see. However the ocean can be many other colors depending upon particles in the water, the depth of the water, and the amount of skylight.

Here are my comments on this subject. Water is clear. I believe the first theory that the blue wavelengths are less absorbed by the water and reflected back to our eyes. I also believe that some of the blue color comes from the reflected sky. My many years at sea, while serving in the United States Navy, indicate that most of the time the ocean water appears green due to the algae content.

I guess the poem IN 1942 just wouldn’t sound the same if it read: “In fourteen hundred ninety-two Columbus sailed the ocean clear.”