system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that some parts of the ocean are clear as glass, some is really blue, and some is like cloudy green?
gpt
The blue color of water is actually intrinsic to water molecules themselves. Vibrational transitions in the molecules have a weak absorption for red light, so the reflected light appears blue. Filtered/clear water will have a natural blue tint. It's very weak though, so there has to be a large volume for the blue color to be apparent. That's why oceans appear blue while a glass of water will appear clear. Keeping this in mind, the deeper the body of water, the stronger the blue color and the darker the water will appear. Bodies of water that do not appear blue have their natural color altered by things like sediment, algae, and micro organisms. These "impurities" can also cause the water to be cloudy as opposed to its natural clear state.