A big sauna with a huge window looking out on the forest and the outdoor hot tub that's big enough for many people to warm up from the cold. This could also be used as a cold pool for dunking after sweating in the sauna.
A Swimming Pool Made From A Shipping Container? This House Has One
Modpools have transformed shipping containers into modern swimming pools with a window. Each pool can be set up in minutes, be made into a hot tub and can be controlled via your smartphone, where you can change the temperature, jets and lighting.
Long narrow pool with separate hot tub / spa - Sydney Waterfront - modern - pool - sydney - Secret Gardens of Sydney custom built hot tub but raised from deck with overflow waterfall drain in center middle.