Am I understanding you properly that the use of the spa is only $9-10 USD!!!!! If so, this seems like a shoe-in to use! And standing naked in front of the airplanes seems a little unusual especially if people can see you, but hey at least you can say you've done that!

Also, if this is outside of customs how does it work for transit pax? Im arriving from FRA on my way to ICN. Do I have to leave customs to go here and then re-enter? Or can I stay on the transit side and use it there. Ill only have 3:05 and also want to visit the Star Alliance lounge as well.