No nonsense answers to questions we are often asked
Does UV light get me if I am in the water?
It depends where you are. You are at
greater risk when on the water - in a boat for instance - than when
in it because of the reflection off the surface of the water which is
added to the normal radiation from the sun.
If you are swimming on the surface of the water, then effectively the water offers no protection at all. Calculations on marine life shows that UV light can penetrate water up to a depth of about 3m but the effective depth is much more likely to be around 40cm, depending on the clearness of the water.