At first blush this seems kind of ridiculous, but the story is pretty cool:
"The sauna was built for a Belgian couple with a bed and breakfast three hours outside of Stockholm who were looking for an environmentally-friendly way to add a sauna without disrupting the forest shoreline. The site of a former wooden pier was chosen to house the new hot house that was built from scratch over a two-week period and treated with the traditional Japanese Yakisugi technique, which burns the wood to treat it instead of using harsh chemicals."
More like this
From the collection WANT: