While Korean-, Japanese-, and Russian-run spots dominate the city’s steam-and-soak circuit, Spanish chain Ancient Bath’s new Tribeca spa Aire—the company’s first U.S. location—is upping the ante on the relaxation front (88 Franklin St., nr. Church St.; 212-274-3777). Aiming to soft-open by the end of this month, the cavernous three-story retreat is the antithesis of a boisterous bathhouse: Only 25 swimsuit-clad visitors are admitted every two hours ($75 for 90 minutes), hundreds of flickering lanterns and candles emit a hazy glow, and voices are kept to a whisper. Bathers can plunge and soak in series of variously sized marble pools and alcoves, including a warm salt pool designed to mimic the Dead Sea, a 350-jet Jacuzzi pool, a 46-degree ice pool, a 61-degree cold pool, a 102-degree soaking pool, and a hammam-like steam room. If you prefer all-out pampering, two private treatment rooms are reserved for one- or two-person three-hour rituals, which include a soak in an olive-oil, a cava, or a red-wine bath and a four-handed massage (from $450).