eli5: Why is water clear in small amount but blue in large amount like an ocean?

Question

I thought it might be the reflection from the sky but if that was the case, why does the ocean appears more blue the deeper you go?

In: 2918

Answer 1

Light going through water has a chance to interact with the water, meaning it gets absorbed or refracted or reflected. The more water it goes through, the more chance light will interact with the water and clarity will drop off.

The light has different frequencies in it, and the different frequencies have different chance of interaction, red light has high chance, blue light low chance.

So the blue color is what’s left of the light traveling through a lot of water, and the clarity dropping off sooner is because of the same interaction.

I.e. the blue light isn’t clear because the light you see is a muddled intensity that can come from anywhere within a large volume.