Hotel Nanpūsō

Hotel Nanpuso keeps two large shared baths in Hakone-Yumoto: Ichi-no-yu (いちの湯) for women and Ni-no-yu (にの湯) for men. Each has its own indoor tub and an outdoor tub built from granite, blue stone, and cypress, right above the Sukumo River. There's no sauna and the baths can't be rented out privately, but the water is soft and smooth on the skin, mild enough for small kids and pregnant guests, and the indoor baths add jet tubs. Only rooms in the Kaze no An (風の庵) category come with their own outdoor onsen tub, filled with heated, diluted spring water; the indoor tub in those same rooms is just plain heated water, not spring-fed. This is a big, long-running hotel, open for six decades now in Yumotochaya, a stretch of Hakone-Yumoto right on the river with mountain views from the windows.