Shinmei Onsen Yumoto Sugishima

Sugishima is a single-inn hot spring standing alone in the upper valley of the Itadori River in Seki City, Gifu Prefecture, deep in the Okumino mountains. A member of the Japan Association of Secluded Hot Spring Inns, it drilled its own source and opened in 1997. The main building is a century-old farmhouse that was dismantled, moved here and rebuilt by carpenters from Hida; its blackened beams and pillars and the sunken irori hearth in the dining rooms preserve the atmosphere of an older Japan. The much-photographed Monet's Pond is about 25 minutes away by car.

The source, named Shinmei Onsen, is an alkaline simple spring classified as hypotonic, alkaline and low-temperature. It emerges at 30.9 degrees Celsius with a pH of 8.89 and a yield of 117 litres per minute, according to the analysis certificate posted at the inn. The water is almost colourless and clear, carries a faint scent of sulphur, and has a notably silky, slippery feel on the skin. Each bath is managed differently: the large indoor bath and the private baths are heated flow-through with no added water and no chlorination, the small indoor bath serves the source unheated exactly as it emerges, and the open-air bath is heated and filtered.

Bathing facilities include separate indoor and open-air baths for men and women plus two reservable private open-air baths named Kogasan and Myojinsan. The inn has twelve guest rooms, including suites with private open-air baths. Day-trip bathing runs from 11:00 to 15:00 with last admission at 14:30, costing 800 yen for adults and 400 yen for children, with discounts for diners. Parking is free.