MARTY PICCO, a 51-year-old software developer in Santa Cruz, Calif., does not seem like a back-to-the-land type. He has an iPhone, an iPad, two MacBooks, two desktop computers, a digital single-lens reflex camera and a plasma television. But when he bought a hot tub, he went for the lowest-tech model around.

Mr. Picco and his wife, Liz, 56, bought a red cedar tub that relies on a wood-fired stove to heat its water, an unusually primitive apparatus in an age of electric fiberglass spas outfitted with hydrotherapy jets, air blowers and underwater lights. The cedar tub, six feet in diameter, seemed to fit better with their home, a mid-19th-century redwood farmhouse, especially when he placed the tub outside in a nest of beargrass and wild sweet peas. But there was more to his choice than that.

“It’s fun, like a ritual that you plan hours in advance,” Mr. Picco said about his simple tub, which he bought a few years ago. “You chop the wood, get the firebox going and get really good at managing the fire to keep the water in a narrow range of 104 to 106 degrees. You have a real outdoor experience, as opposed to a Las Vegas experience.”

By all accounts, rustic wood-fired hot tubs constitute a tiny niche of the broad hot-tub market. Their most prominent manufacturer, Snorkel Hot Tubs in Seattle, estimates that it has sold a total of 15,000 tubs, a mere drop compared with the 6.3 million conventional hot tubs installed in the United States, according to the Association of Pool and Spa Professionals in Alexandria, Va.