The town bathhouse in front of Unazuki Onsen Station, gateway to the Kurobe Gorge Railway. A bright white bathroom with tubs of Kurobe granite holds crystal-clear, mildly alkaline water said to be Japan's most transparent. Just ¥510, with a free foot bath, drinking fountain and rooftop terrace. Easy to fit in before or after the gorge train.
Next to the Himi Banya-gai seafood market near the port famous for winter yellowtail, a day spa fed by its own well 1,250 m down. The brown, strongly saline water flows freely, and on clear days the rotenburo frames the Tateyama range across Toyama Bay. Open 10:00–23:00, from 7:00 on weekends and holidays. ¥950. The classic routine: kaisen-don or conveyor sushi at the market, then a soak.
Ten minutes by car from Kurobe-Unazuki-Onsen Station on the Hokuriku Shinkansen, a large day-spa wing of the lone inn Kintarō Onsen in Uozu. Its sulfur-rich sodium-calcium chloride water is among the most concentrated in Hokuriku, gushing at 1,800 litres a minute. A giant rock bath built from Tateyama boulders, open-air baths, a carbonated bath, rock-bath rooms and four private baths; open daily 8:30–23:30. Admission ¥1,100.
A city-run day bath on the shore of the Unazuki dam lake. From the lakeside open-air bath you can watch the Kurobe Gorge trolley train crawl along the far cliff — a favourite with railway fans. Just ¥510 including shampoo and hairdryers, with silky mildly alkaline water. Open only from late April to early December; closed in winter. Five minutes from Unazuki-Onsen Station by the free 'EMU' shuttle or car.
About 12 minutes on foot from Murodō terminal, the hub of the Tateyama-Kurobe Alpine Route, this inn at 2,410 m is Japan's highest hot-spring lodging. Milky acidic sulphur water piped from Jigokudani flows 100% free, and outside the window is another world: the 3,000-metre Tateyama range and the volcanic lake Mikurigaike. The bath is indoor only; day use 09:00–16:00, ¥1,100 for adults. The café's blueberry soft-serve and curry are favourites. Open only during the mountain season, mid-April to late November; closed in winter. Especially busy during the Snow Corridor (Apr–Jun) and autumn colours (late Sep–early Oct). With the altitude and strong water, keep your soak short.
A town-run day spa inside the hilly 'Toyama Forest of Health – Green Park Yoshimine', about 15 minutes by car from Tateyama Station, the Toyama gateway to the Tateyama-Kurobe Alpine Route. The clear, mildly alkaline simple spring is piped straight from the source and called 'beauty water'; besides the main bath there is a rustic rock open-air bath, an herbal bath and a sauna. From April 2026 adults pay ¥750 and children ¥380; open 10:00–21:00 (last entry 20:30), closed Tuesdays (plus maintenance days). The park has a campsite, barbecue area, park golf and the Yoshimine Heights lodge, making it a handy stop before or after the Alpine Route or a Tateyama climb. About 5 minutes by car from Iwakuraji Station (Toyama Chihō Railway), 20 minutes from Tateyama IC; 300 parking spaces.
A day spa beside the 'Kamon Park Shinminato' roadside station in Imizu, on Toyama Bay. Its spring is a dense chloride water said to rank among the richest in Japan in dissolved minerals, with several times the free carbon dioxide of shop-bought bath fizzers, so onsen enthusiasts know it as a genuine carbonated chloride spring. The tea-brown, salty, iron-rich water warms you deeply; there are indoor and open-air baths, a sauna and a cold plunge. What stands out is the long day: an early-morning bath from 05:00 through to midnight (23:00 on Sundays), with cheaper early and late rates. Regular admission is ¥970 for adults (¥1,020 weekends and holidays), ¥750/¥780 early or late, ¥520 for children. Closed Mondays (open if a holiday, then closed the next weekday) and January 1. Easy to pair with the Shinminato Bridge, Kaiwo Maru Park and seafood at the Shinminato Kittokito market; about 10 minutes by car from Kosugi IC or 20 minutes by community bus from JR Kosugi Station.
A 400-year-old hot spring inn standing alone deep in the Ogawa river gorge that runs down from the Northern Alps in Asahi, the easternmost town of Toyama. Known as a fertility and therapeutic spa, it offers a circuit of five different baths. The great curiosity is the 'natural cave open-air bath', a dome of travertine built up over centuries from the spring's own mineral deposits and designated a prefectural natural monument – bathing inside it is an experience found nowhere else in Japan. There are also the streamside Renge-no-Yu outdoor bath, a rock bath and a cypress tub, all with free-flowing bicarbonate spring water that keeps you glowing long after. Day bathing runs 9:00–15:00 (reception until 14:30) for ¥1,000 per adult and ¥500 per child, or half price for the outdoor baths only. Irregular closures, and the two outdoor baths shut for winter from 1 December until the mid-April thaw. About 15 minutes by car from Tomari Station on the Ainokaze Toyama Railway, 30 minutes from Kurobe-Unazuki-Onsen Station on the Hokuriku Shinkansen (shuttle for overnight guests) or 15 minutes from Asahi IC. A hidden spring to pair with the Jade Coast and Unazuki on a drive along the Niigata border.