Postscript note: I've published an update to this post here: Jennifer's wood-fired bathtub revisted
Last summer I got to visit my buddy, Jennifer, at her home in Homer, Alaska. Recently she has (mostly) completed a couple of additions to her spread: One is a sauna. The other is her outdoor bathtub. Both are awesome and merit sharing with the world.
Here is her sauna:
It's not technically finished yet insofar as it hasn't been christened formally as a sauna. Instead she has used it as a guest cabin for visitors and WOOFERS (willing workers on organic farmers).
Here is the bathtub:
The bathtub is pretty rudimentary but it does the job, providing a blissful hot soak outside in nature. As you can see, the tub sits on the ground somewhat recessed into an inclined slope. A fire box has been built out of mud under the tub. It is closed by an old door from a cast iron wood stove that was salvaged (along with the tub) from the Homer dump. You can see the chimney out the back.
It takes a few hours but it's fairly easy to warm up a bath in the summer time. Water temperature is regulated by a combination of fire stoking and adding cold from the hose.
When the bathing is complete the water is recycled into her garden by syphoning it with another hose.
Here you can see how water can be feed into the garden and green house.