First off, these indeed are waterproof or at least very water resistant. YES, water CAN enter the housing. However, the actually LED's themselves are sealed in resin so the water in the housing doesn't affect the circuits. I was having many problems with another set of lights that were non-LED and claimed to be waterproof. It got to the point where after every trip a bulb was out and I had to take the light apart to clean the corrosion off the contacts. These lights are bright, good quality, and so far have held up well. I use them on my duck hunting boat trailer which sees MANY dips in saltwater every year. Since putting these lights on they work just fine with no issues.
Rating: [5 of 5 Stars!]