While looking at a few different motors and ESCs on hobbyking I came across their "Boat ESCs". Particularly this one: http://www.hobbyking.com/hobbyking/stor ... _UBEC.html .
In the picture it appears to be fairly water tight and in the comments people make mention of it being waterproof. Do you think this is "waterproof" as in it can get splashed on safely, or "waterproof" as in it can go down 15-20 feet in the water for 30 minutes at a time?