Yubara Onsen Sunayu

Free, 24 hours, on the riverbank below the dam — the “West Yokozuna” of natural open-air baths

Suna-yu is the symbol of Yubara Onsen in Maniwa, Okayama: a natural mixed open-air bath on the gravel bank of the Asahi River directly beneath the 74-metre Yubara Dam. Alkaline simple spring water rises by itself between the pebbles of the riverbed — three tubs at different temperatures (Beauty, Fertility and Longevity baths) floored with sand and gravel, the huge dam wall behind and river and mountains in front — a wild setting that has earned it the title of “West Yokozuna” in Japan’s open-air bath rankings. Most remarkable of all, it is maintained by local volunteers and is free 24 hours a day, so you can soak under the stars at night, in river mist at dawn, or in falling snow in winter, another of its specialities. But it is genuinely mixed and in full view of the road and bridge: men cover themselves, women customarily wear a bathing wrap rented from a nearby ryokan or the tourist office, or a bath towel, and soap and shampoo are prohibited — to wash, pair it with Yumoto Onsenkan (¥800) in the centre of town. Closed for cleaning on Wednesday mornings and the first Friday of each month from 10:00 to 14:00. The water flows straight from a 43 °C source and is on the tepid side, easy to linger in, and leaves the skin smooth.

Tips & cautions

- No bathing during cleaning (Wednesday mornings, 1st Friday 10:00–14:00). Closed in heavy rain or high water.

- Mixed and visible from the road: for women a bathing wrap (rented at the tourist office or ryokan) or a bath towel is all but essential; men cover up with a towel. Swimwear is generally tolerated, but check the signs on site.

- No soap or shampoo; no photography (respect other bathers).

- Changing huts are basic and unattended — don’t leave valuables. Lighting is dim at night; a lantern helps.

- The gravel floor can hurt your feet — bring sandals.

- The water is tepid — in winter, warm up quickly after getting out.

- Tattoos: no rule, but this is a bath kept by locals — be respectful.

- 5 min on foot from the spa street; pair with Yumoto Onsenkan (¥800, sauna).

Getting there

Maniwa community bus toward Hiruzen Highlands ~40 min from Chugoku-Katsuyama Station (JR Kishin line) to “Yubara Onsen”, then 10 min on foot (Yubara-Onsen, Maniwa, below Yubara Dam). By car ~5 min / 3 km from Yubara IC (Yonago Expressway); city-run free car park, ~50 spaces. ~1 h 30 min from Okayama city. Enquiries: Yubara Tourist Information Centre, 0867-62-2526.