39 Underground Sauna

39 Underground is a four-floor local gay bathhouse near Saphan Khwai BTS in Bangkok's Phaya Thai district, a little away from the main Silom scene and all the more appealing for it. Known by locals as "Sam-Kao," it's a friendly, unpretentious spot popular with Thai guys, with a dry sauna, steam rooms, lockers, cabins, cruising areas, and a rooftop, plus theme nights like the Friday masked party. Affordable and refreshingly low on tourists, it's notable as one of the few Bangkok saunas that are genuinely busy during the daytime, drawing a mostly local, mixed-age crowd from early afternoon onward.