While most submersible trailer lights are waterproof, there are many different types of materials in which these lights may come packaged, and you will need to read on how each type protects against water damage. If you're going to have your submersible trailer lights in the water, it's best if they are waterproof. This is because no matter how careful you try to be, the fact remains that there will always come a time where they'll fall into the water. And this can spell disaster for any non-waterproof light fixtures onboard, such as LED bulbs.