When we go camping there is usually water nearby. Usually a lake or river. As long as it isn't lightening we get out and go swimming in the rain! I let the kids run around in the rain and play like they normally would. If it's just me and my husband I put a tarp over a hammock and relax in it while reading. Unless it's lightening we really don't do anything different. If it's lightning and our car is anywhere near where camp is, (campground) we go out to eat somewhere and come back when the bad part is over.