Okaya Onsen

Okaya Onsen is located in Okaya City, Nagano Prefecture, on the eastern shore of Lake Suwa — Japan's largest lake in the inland mountain regions and a sacred body of water central to the faith of Suwa Grand Shrine, one of Japan's oldest and most important Shinto institutions whose upper and lower shrines are separated by the lake itself. The siliceous thermal waters here complement a city historically known as the global center of the silk reeling industry during the Meiji and Taisho eras, when Okaya's precision machinery and skilled female workers produced raw silk that was Japan's most valuable export, connecting this landlocked mountain city to the global luxury textile trade. Bathing at Okaya Onsen on the shores of sacred Lake Suwa — whose dramatic mid-winter ice formations (omiwatari) were historically interpreted as omens by Suwa's Shinto priests — provides a deeply culturally resonant mineral spring experience in one of Nagano's most historically layered lakeside cities.