Maintopia Besshi is a tourist complex and roadside station in the mountains of Niihama City, Ehime Prefecture, built on the industrial heritage of the former Besshi Copper Mine, once known as one of the largest copper mines in the East. On the fourth floor of its main building sits Besshi Onsen Tenku no Yu (Sky Bath), a day-use hot spring perched at roughly 170 meters elevation in the Hadeba area, overlooking the deep mountains and the Kokuryo River gorge. Reopened on April 15, 2016 after a complete renovation of the former Healthy Land Besshi facility, it has become one of Niihama's most popular bathing destinations. The source is the Besshi Kosen No. 3 Spring, classified as a sodium-calcium chloride-bicarbonate cold mineral spring (hypotonic, neutral, cold mineral spring) with a pH of 7.1. As a cold spring it is heated for bathing, and the water is said to be effective for neuralgia, muscle and joint pain, chills, frozen shoulder, bruises, sprains, chronic digestive issues, hemorrhoids, recovery from illness, fatigue and general health promotion. The facility offers two themed bathhouses, the Wood Bath and the Stone Bath, which alternate between men and women roughly weekly. Each features a main pool, an open-air carbonated spring (around 37.8 C) and oxygen spring (around 42.6 C) created with technology from a local Niihama company, plus tsubo-yu jar baths, lie-down baths, jet baths, a far-infrared sauna, a cold plunge and outdoor relaxation spaces. Rock baths and salt rock baths are available for an additional fee, and the complex also includes the Mori no Kaze restaurant, a kids park and the historic mine tour, making it a destination for a full day out.