Yubara Onsen Sunayu | 湯原温泉 砂湯（露天風呂）
Widely celebrated across Japan as the undisputed ‘Yokozuna of Western Japan Open-Air Baths’ (西の横綱), Sunayu (砂湯) at Yubara Onsen is one of the most iconic and authentic wild thermal springs in the country. Nestled directly beneath the towering wall of Yubara Dam along the rushing waters of the Asahi River, this legendary natural hot spring bubbles straight up through gravel sand on the riverbed at an immaculate 45°C–47°C.
Unlike commercial resort waterparks, Sunayu is completely free, open 24 hours a day, and operates as a traditional, respectful mixed-gender open-air bath (konyoku). Three distinct natural stone basins—affectionately named Bijin-no-yu (Beauty Bath), Kodakara-no-yu (Fertility Bath), and Chōju-no-yu (Longevity Bath)—offer different temperature gradations surrounded by misty mountain forest.
Bruce’s Lived Experience Note: Sunayu is one of my personal favorite day-trip excursions from Mimasaka. For the most tranquil experience, visit during early morning twilight or late evening under a canopy of mountain stars when mist rises off the river. While men generally use modesty towels, women can rent specialized modesty bathing wraps (yami-gi) at the nearby Yubara Tourist Information Center. Don’t miss this raw taste of authentic Japanese onsen heritage!
【 日本語情報 / Japanese Overview 】
公式概要| 名称 | 湯原温泉 砂湯（天然大露天風呂・足元湧出源泉） |
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| カテゴリー | 天然露天風呂・秘湯・共同浴場・混浴温泉 |
| 所在地 / エリア | 岡山県真庭市湯原温泉9（旭川河川敷・湯原ダム直下） |
| 概要 | 全国露天風呂番付で「西の横綱」にランクされる岡山屈指の天然大露天風呂。湯原ダム下の旭川沿いに位置し、川底の砂から良質なアルカリ性単純温泉が自噴する「足元湧出」が最大の魅力。24時間年中無休・無料で開放されており、温度の異なる『美人の湯』『子宝の湯』『長寿の湯』の3つの湯船を大自然の中で堪能できます。 |
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