the human eye sees the ocean as blue due to light waves coming from the sun and the distance a person is from a water source when the sun shines on the ocean, only green and blue spectrum of light gets reflected back this is why the ocean seems blue the color of water can also seem very different depending on the distance you are from it a bathtub or glass full of water always looks clear in deep water the ocean only transmits a small amount of blue light so it looks dark blue