Onsen

Onsen is the Tenderloin's Japanese-inspired bathhouse: a 104-degree communal tub, redwood sauna, steam room and overhead cold plunge under a skylight.

Onsen is the Tenderloin's improbable sanctuary, a Japanese-inspired bathhouse behind an unmarked door on Eddy Street that reopened in April 2025 under new ownership. The bathing room is the draw: a 104-degree communal tub under a skylight, a redwood sauna, a steam room and a custom overhead cold plunge, all wrapped in old brick and greenery, with a small restaurant and tea service attached. Sessions are timed and intimate, and the week alternates between men's, women's and co-ed days. The bathing room The operator's own inventory is exact: a 104 degree communal tub, redwood sauna, steam room, custom overhead cold plunge and western style showers.

Redwood-lined dry sauna off the main bathing room.. Listed amenities: Cold shower, Showers, Towel rental, Hot pool / hydrotherapy, Steam room.

Listing type: Public bathhouse. Access: Reservation. Listed capacity: About fifteen bathers; bookings up to four together. Cold plunge: A custom overhead cold plunge beside the sauna and steam room.. Reserve a bathing session through Onsen's booking page; sessions are timed, robes, towels and sandals are included, and groups book up to four together. Check the week's calendar for men's, women's and co-ed days. SaunaShare records this listing as editorially reviewed by SaunaShare. A listing label describes where the information came from, not the quality of the sauna. Listing details were last reviewed on August 25, 2026.

SaunaShare does not process bookings. Confirm current hours and rates with the operator, and book on their own page.

SaunaShare is a JavaScript application. Enable JavaScript for the full experience, or use the links below to browse the directory.