
Owari Onsen — photo: Asturio Cantabrio · CC BY-SA 4.0 · Wikimedia Commons
Search for an onsen in Nagoya and you get hotel baths, big day spas, a theme-park resort and a few towns an hour or two away, all in one list. The short answer: there is no onsen town inside Nagoya City in our records. But the flat land just west of the city, around the mouths of the Kiso rivers, has some of the hottest water close to any big Japanese city. Four places within 30 km of Nagoya Station come out of the ground at 42 °C or more. This guide goes through them with the numbers.
Our records hold 1,538 onsen across Japan. Aichi Prefecture, which Nagoya is the capital of, has 16 of them. None is inside Nagoya City. Twelve of the 16 have a recorded source temperature, and three reach 42 °C: Owari (50.3 °C), Tobishima (46.8 °C) and Minami-Chita (45 °C).
Measured in a straight line from Nagoya Station, nine onsen lie within 30 km, across Aichi, Gifu and Mie. Eight have a recorded temperature, and four reach 42 °C, roughly the point at which a bath can run without a boiler. All four are on the low ground to the west and south-west, between the city and the Kiso, Nagara and Ibi rivers. That is a better result than Tokyo or Osaka, where the near springs are mostly cool.
So the useful question is not "is there an onsen in Nagoya" but "how far west am I willing to go". Fifteen minutes on a train gets you to hot water. An hour or two gets you to a real onsen town.
The other five within 30 km are cooler. Hashima (20.4 km) is 37 °C, Nannō (26.0 km) 36 °C, Tado (26.6 km) 38.8 °C at pH 8.6, and Anpachi (27.6 km) 7.8 to 30.2 °C. Utsutsu, 24.1 km north-east in Kasugai, is the only one on the hill side of the city; we have no temperature for it, but it is recorded at pH 4.6, mildly acidic.
Inside Nagoya, a few hotels and spa complexes advertise 天然温泉 (tennen onsen), natural hot spring water, from wells they drilled themselves, some of them in the middle of the city. That is legitimate, and for an evening after a day of sightseeing it may be all you need. But these are single buildings, not onsen towns, and they are not in our records. Look for the spring analysis board near the changing room to see the temperature and whether the water is heated or recirculated; how to read it is in onsen vs sento.
Three places come up again and again in searches from Nagoya. They are close, but none of them is a classic old onsen town.
On the coast to the south-east, the Mikawa Bay towns are inn towns by the sea: Nishiura (52.1 km, seven lodgings), Katahara (47.6 km, seven lodgings, by Katahara Station on the Meitetsu Gamagōri Line) and Miya (52.9 km, 35 °C, nine lodgings, near JR Mikawa-Mitani Station). At the tip of the Chita Peninsula, Minami-Chita is recorded at 45 °C, reached by bus from Utsumi Station on the Meitetsu line.
If you want a town of inns and public baths, with water that is hot at the source, you are going for a night, not an evening. The three best onsen near Nagoya picks Gero (84 °C, about an hour and 40 minutes on the JR Limited Express Hida), Hirugami (by highway bus) and Yunoyama (by Kintetsu and a local bus), with the numbers behind the choice. For the mountains beyond Gero, see Japanese Alps onsen.
Several of the hot springs near the city are single day-bath facilities, not towns, so check the opening hours and whether they close one day a week. Hotel baths are usually for guests only.
Tattoo rules vary from one place to the next, and large spa complexes are often the strictest. See going to an onsen with tattoos, and check with each place.
The rules are the same in a city spa as in a mountain inn: wash before you get in, keep the towel out of the water, and keep your voice down. Onsen etiquette has the full list.
For the same question in other cities, see onsen in Tokyo and onsen in Kyoto and Osaka. Flying into Chubu Centrair? Onsen near Japan's airports measures from there. For a bath without staying the night, see onsen day trips.