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

I realize this isn’t very satisfying, but water looks blue because it is very slightly blue. Water absorbs other colors, but allows blue light to pass through, meaning it is blue. In small amounts of water the blue isn’t noticeable, but it becomes noticeable when there is more – that’s why the deep end of a pool looks like a darker shade of blue than the shallow end. You see the same thing with sheets of clear glass – a very thin sheet of glass will not seem to have color, but a thicker sheet will.

There are also generally impurities in water that will affect the color. In most swimming pools you have chlorine, which affects thing.