Snorkel makes hot tubs that are heated with wood fires. The stoves are actually submerged in the tub. Basically, you prepare a fire on the bottom of the stove with paper, kindling, and then small logs. When you slide the door over the firebox opening, the stove begins to heat the water. See their FAQ page for more information. The cost of a tub and stove is about $2200-$3000 — these can be purchased separately too.The tubs are patterned after a centuries old design and are made from the kiln dried Western Red Cedar and Redwood. We previously featured SeaOtter Woodworks who make similar wooden hot tubs.
Their site contains images of a goodly number of elves or hobbit-like creatures taking baths. You have been warned.