Partisans Grotto Sauna, Canada

Curving along 800 square feet of ancient rock on Sans Souci Island off Toronto, the private Grotto Sauna by PARTISANS was inspired by the natural caves and waterways of the region. A Leica 3D scanner was used to create a site model before working on the rock itself. The fluid interior is clad in locally sourced cedar with a parallel grain, which is not only warm and aromatic but also rot resistant. But the best part about this stylish steam chamber is its views of the Lake Huron sunset—ranked one of the best in the world by .

Saunalautta, Finland

Built by a group of friends in the sauna heaven of Finland, this DIY floating raft offers a BBQ, hammocks, and a rooftop terrace for summer plus a sauna for warming away the winter—internal temperatures can reach up to 194° F. The wood-and-metal structure floats atop recycled plastic drums. Overnight reservations can be made through Saunalautta’s Facebook page.

Jensen & Skodvin Sauna, Norway

The subterranean river sauna at the Juvet Landscape Hotel near the National Tourist Route in Western Norway takes the prize for best view. The raw concrete and rusted metal capsule, designed by Jensen & Skodvin, has a central glass window that opens up to a winding river. Its other three sides are covered by earth, blending in with the boutique hotel’s 10 stilted rooms built of pine and glass.

Jonas Wagell’s Arjan Sauna, Scandinavia

Swedish designer Jonas Wagell conjured a range of minimalist sauna houses inspired by Finnish singer, artist, and sauna enthusiast Arja Saijonmaa. The Arjan Sauna comes in 12 different models, all topped with living roofs, fit for a variety of Scandinavian landscapes. Cabins range from about 25 to 50 square feet and can be hooked up with electricity or be left as rustic nature retreats.

Bio-Hotel Stanglwirt, Austria

Nestled at the base of Mount Kaiser in Austria, Bio-Hotel Stanglwirtoffers an old-fashioned dose of rustic luxury. Food comes straight from the hotel farm; rooms are heated by a low-energy pump, and the 40-person event sauna looks out over the property’s natural spring and the Kaiser mountain range in the distance.

Surf Sauna, United States

A sauna session has never been this intimate or immersive. A group of hardcore New Hampshire surfers built this barrel sauna out of western red cedar and stainless steel to thaw out after riding the Northeast’s frosty winter waves. Lucky for us, the Surf Sauna is available for rent by the day, so sports enthusiasts of all sorts can tow it to the winter playground of their choice.