How to water-proof electronics ??

[snowboi1289]

With my Silverado project almost completed,I'm thinking about building a new mud track.I want to go as deep as I can with the truck in mud,but I ran into a problem,the electronics will get wet very easily.I know there is a couple stuff that I can use like plastic wrap,but I dont wanna use that(because theres still a chance that water can leak through,because the motor and board might get hot and burn the plastic).If theres a grease or glue or something that,please tell me..