Stars twinkle faintly in the smoggy New York sky, barely visible to the guests on Le Bain’s rooftop bar as they recline on pink waterbeds and gaze upward. Fortunately, celestial bodies aren’t the stars at this bi-level 18th-floor playground, which opens its rooftop in the spring and maintains a steady flow of high-profile clientele throughout the year. Regardless of season, topless models splash in hot tubs and tall windows offer panoramic views of downtown Manhattan and the Hudson River. Bartenders sling cocktails in the lower-level lounge as guests dance to a lively mix of hip-hop, electronica, and rock. Others line up at a vending machine peddling colorful bikinis and board shorts, eager to take a swim in the lounge’s heated pool. A graffiti-splashed staircase leads to the rooftop, where the cool night air offers reprieve from the rollicking party below. White-clad waitresses float across the AstroTurf lawn, carrying trays of cherries and fruity cocktails. Well-dressed guests take off their shiny heels and custom-tailored hot-dog suits while marveling at the view, relaxing on waterbeds, lawn chairs, and pristine white towels. Come daytime, sunbathers replace the late-night revelers, basking in the sun and nibbling on smoked-salmon crepes.