Brooklyn Banya and the Mermaid Spa, located in Kensington and Sea Gate, respectively, are filled with locals looking to get warm and catch up with friends - not so much for a lush afternoon at the spa. ➽ For a more old-world Russian vibe, take the Q train. Regulars say the rooms are significantly hotter on Boris weeks. Bathers on Boris weeks use a paper punch card those who go on David weeks use a digitized swipe pass and can often find a Groupon deal. ➽ At the Russian & Turkish Baths, check the calendar for “Boris weeks” and “David weeks.” Both owners have retired from East 10th Street, but their heirs continue to run the business on alternating weeks - an arrangement from the 1980s based on a mysterious feud. At King Spa & Sauna and K-Town Sauna, you’ll go naked - policy prohibits any attire in their gender-segregated steam and treatment rooms.

You’ll need a swimsuit if you’re heading to a venue with co-ed rooms and pools (this includes the Mermaid, SoJo, and Bathhouse, below).

Most bathhouses provide towels, robes, clean shower sandals, and, if you’re at a banya, a wool hat to protect your head from the heat. ➽ Pack a swimsuit and an ID for locker rental. For a New Age atmosphere - with an Amit Greenberg mural and a flotation tank - go to Bathhouse in Williamsburg, which opened in November. Wall Street has a grander lounge area, while the Russian & Turkish Baths draw a more diverse crowd, from NYU kids to old Slavic men to, at least recently, Owen Wilson. There’s the Wall Street Bath & Spa and the 128-year-old Russian & Turkish Baths in the East Village, which are the city’s true banyas: The stone-and-wood rooms are bare-bones but clean.

➽ New shvitzers should start with a day pass, ideally to a place with a standard menu of thermal soaking pools, cold plunge tubs, steam rooms, and dry saunas.

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