add lavender oil into a bucket full of charcoal that is hot and steamy.As soon as you do that the lavender scent will come out , it is very relaxy to do that way, better, and you will feel refreshed and sleep much better at night.
Find traditional wood fired saunas at Cedar barrel Sauna. Wood fired saunas offer warmth, a pleasant sauna experience, and the additional advantage of fragrant wood in your sauna. They also offer wood fired or burning sauna heaters.
Someone suggested an aquarium heater to warm the water to 90 degrees. Others suggested a rain barrel or other means to catch rainwater could flow into this. ****** ******* Outdoor shower for really stinky people