Why does the ocean look blue?

Water absorbs the red part of sunlight more readily than the blue part. The light left for us to see often looks blue.

Particles and tiny organisms can change the color. That helps explain why the sea can also look green or brown.

A small glass can look clear because light passes through only a little water. Through a much longer stretch, water’s uneven absorption of colors becomes easier to see. So the amount of water in light’s path matters, too.