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

We see color as light reflected off an object. Water doesn’t just reflect, but also refracts, changing the wavelength of light as it gains angular momentum, like the prism on the pink floyd record album. As the wavelengths stretch, they blueshift, making the light appear blue. This can be affected by contaminants, as others mentioned, but looking at pure sea ice from an iceberg you can see a much denser block of water that is much more deep blue, despite having ZERO impurities. So the top comment is correct-ish, but not complete, or accurate enough for a 5 year old