Water Cooled Equipment

We have all heard of water cooled computers, but is there such a thing as water cooled transmitters? My part 15 transmitters are not leak proof, but I am considering dabbing some roofing tar into the cases to see what we can come up with. Anyway, this line of thinking has been brought about by the bold experimentation of YouTuber Mattias Krantz, who was not exactly trying to cool his piano, but check this out:

A Piano Submerged