Hirauchi Kaichu Onsen, Yakushima Island

Located at the south of Yakushima Island（屋久島）, the Hirauchi Kaichu Onsen（平内海中温泉） is a natural hot spring along rocky shore. As the hot spring water gushes from below sea level, this hot spring only appears for about five hours during low tide. There is one other such hot spring in Yudomari（湯泊） nearby.