Onsen

Owners Caroline Smith and Sunny Simmons, an artist and a furniture builder, respectively, opened this Tenderloin haven in 2016 after a cross-country tour soaking in bathhouses across Japan. The resulting space is beautifully designed—all the more surprising for its past life as a former auto mechanic’s garage. In front, you’ll find a teahouse and restaurant; in back, a skylit, plant-laden oasis that includes six private treatment rooms for massage, facials and Reiki; a 104-degree communal soaking tub (the former mechanic’s pit); a redwood-cedar sauna; a steam room and cold plunge showers. Your bathing experience here will depend on the day: Wednesday and Thursdays are bathing-suit optional, though Wednesdays are for men only and Thursdays are solely for women. (Bath products, towels, robes and hot tea are complimentary.) The beauty is in the artful details, from the glowing wall of Himalayan pink salt in the sauna to the steam room’s black and white zigzag tile inspired by California artist Orr Marshall.