I have been nude with others in swimming situations twice...it was mostly because it was silly to make a special effort to have a swim suit in a secluded place. It was quite pleasant, but going out of the way JUST to be nude in an airplane seems odd to me....as it would if I were hiking in the woods..etc.
   There are just too many things that are dangerous and/or uncomfortable with no clothes...and I sunburn easily. Swimming nude makes sense, playing darts doesn't.