Water has no color. It appears to be blue in large quantities because blue is the widest color of the light spectrum and the water also reflects the sky above it.
Different colors can penetrate deeper into the water. Red is the color that can be seen the furthest down into the water because red light has the shortest wavelength and the most energy. This is why fishermen sometimes use red lures to catch large fish in deep waters, because the red lures are the only things that can be seen.
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