Coming from a sail boat background, we're aware of several 12V
lights that can be used outdoors on a boat. These lights have seals that allow exposure to more moisture, which promotes corrosion.
We installed this Perko light in the shower of our 1974 31' center bath. The switch is very water resistant (i.e. corrosion resistant). Obviously, the light was installed away from the direct stream of the shower. Yes, it does use a type 1156 bulb, so it draws more amperage. We only used when showering to minimise the power draw (and we lived to tell this tale . . . .)