Futamata Radium Onsen is a historic therapeutic hot spring resort located in a valley upstream of the Kawamata River in Oshamambe Town, Yamakoshi District, Hokkaido, with a history dating back to the Meiji era. Its greatest feature is the giant 'travertine dome' formed by calcium carbonate deposits from the hot spring water, designated as a Hokkaido Natural Monument in 1965.

The travertine dome is deposited over approximately 400 meters in length and 200 meters in width along the upstream Futamata River, reaching a maximum height of 25 meters. Travertine domes of this scale exist in only two places in the world: Yellowstone in America and here at Futamata - making it an extremely valuable geological resource. The travertine contains 95.75% calcium carbonate.

The spring quality is characterized by containing trace amounts of radium beneficial to health and no sulfur content. It maintains sufficient hot water volume through natural flow without drilling, allowing guests to enjoy natural flowing hot spring water.

Bathing benefits include neuralgia, rheumatism, infertility, chronic skin diseases, sprains, and more. For drinking, it is said to be good for chronic digestive diseases, diabetes, liver disease, and cystitis. The radium-containing spring water is believed to contribute to health promotion through hormesis effects.

The facility is a single inn with 53 Japanese-style rooms (9 with toilets) and a total capacity of 130 people, operating as a large-scale therapeutic hot spring resort. Wi-Fi equipment is available, and training equipment can be used free of charge. There is also a banquet hall for group use. While maintaining the function and atmosphere of a therapeutic hot spring resort, there are no self-catering facilities.

From the outdoor bath, you can see the travertine dome rock formation up close, enjoying the natural sculptural beauty while soaking in the hot spring. Many visitors come for long-term stays for therapeutic purposes, beloved by people who thoroughly engage in hot spring therapy.

Known since the Meiji era as a therapeutic hot spring resort where people gather, it continues to receive high praise from hot spring enthusiasts and therapeutic visitors as one of Hokkaido's secret hot springs. It is a unique hot spring facility that cannot be experienced elsewhere, combining the world-rare geological resource of the travertine dome with quality radium-containing hot spring water.