Kawayu Onsen

Little knownBarely documented in English. This is the kind of place the site exists for.

Researched and written by Hinato

Kawayu OnsenSenninburoriver bathHongufree onsen

Photo: Nekosuki / Wikimedia Commons (CC BY-SA 4.0) · original

A good onsen visit is mostly about timing, and Kawayu Onsen is no exception — when you go changes what you get.

At Kawayu the hot spring comes up through the gravel bed of the Oto river, which means that if you dig a hole in the riverbed it fills with hot water. In summer people do exactly that — the inns lend spades to guests and you make your own bath on the shingle, sized to taste.

From December to the end of February the village goes further and dams a section of the river to make the Senninburo, the thousand-person bath: an open-air pool of about a thousand square metres in the middle of a river valley, free, open from half past six in the morning until ten at night. There is no roof, no wall and no charge. Swimsuits are normal. It is a fifteen-minute drive from Kumano Hongu and it is one of the strangest and best things in Japan.

What to know before you go

When to visit

December–February for the Senninburo | Summer for digging your own

Time to allow

1–1.5 hours

Bathing hours

Senninburo 6:30 AM – 10:00 PM, December to the end of February | Self-dug riverbed baths March–November

Closed: Senninburo runs December–February only | Unusable in high water

Fee

Free

How to reach the baths

Directions to the baths

Kawayu, Hongu-cho, Tanabe. By bus from Kii-Tanabe or Shingu toward Hongu. The Senninburo river bath runs from December to the end of February, 6:30 AM – 10:00 PM, and is free. From March to the end of November you can dig your own riverbed bath; inns lend spades to guests free of charge. Swimsuits are the norm. The bath is subject to river conditions and high water.

What locals know

**December to February for the Senninburo.** The dammed thousand-square-metre pool only exists in those three months. Outside them you dig your own. **Bring or borrow a spade in summer.** Inns lend them to guests. Digging a hole in the gravel and waiting for it to fill takes ten or fifteen minutes and is the whole activity. **Swimsuits.** This is an open riverbed in public view and swimwear is standard, unlike an ordinary onsen. **Arrive changed and bring a towel.** Facilities at the river are minimal. **High water cancels it.** It is a river. After heavy rain the bath is gone or unusable — check with the tourism association before travelling in wet weather.

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