Hirauchi Kaichu Onsen is a rare type of hot spring, with its water source coming from within the ocean. There are two natural baths, created by modifying natural depressions on the shore. Bathing here is only possible during low tide: twice a day and two hours at a time. Enjoying this hot spring during the daytime while gazing out at the sea or at night while admiring the starry sky and the soothing sound of the waves is an excellent way to relax.