I'm in Yakushima. Today I went scuba diving. I can now confirm that there are fish in the ocean near Japan.
Also included in the guided scuba trip is a stop at a hot spring afterwords. We stopped at Yudomari, which is outdoors and right by the ocean. I must admit, the onsen concept has grown on me. I also like that it's included in the scuba trip package. It's like if outdoor guides in America were to include nude hot tubbing as part of the package. I'm sure that would work out well.