Kawayu-Onsen is one of those picturesque onsen towns. This is one is not very easy to reach, as are most town like this. I'm sat in Shiretoko, and it requires a long and slow train ride to Kawayu-Onsen. And then, a bus ride to the inner town. But then, you're treated with lots of nature-related activities and of course an array of bath houses. Also, a sulfurous mountain.