For a day by the water with a difference, organize an outing to the bubbling pools of Ishiyu. This place is famous for its mineral-rich thermal waters.
This naturally heated water source in Ueda comes recommended by fellow travelers, so be sure to put it on your travel itinerary. However, your day doesn't end there. There are many more places waiting for you to discover after Ishiyu. Mugonkan, Kitamuki-Kannon Temple, and Anrakuji Temple are not far away.