Along Lake Kussharo in the tiny town of Kotan, the locals have created a rotenburo (outdoor hotspring) bordering the lake. We visted this December with a temperature of -5 C in a gale that must have had a windchill factor of -20, or so.
Disregarding the outside temperature, I got into the bath and enjoyed a nice soak as the water had a great temperature. However, getting back into my clothes was freezing cold but I wouln’t liked to have missed this experience for the world!
Access to the rotenburo is free of charge.