Sojo Spa Club

O.K., so technically this spot isn't in NYC proper, but to experience the country's largest and most accommodating Korean Spa, it's worth the quick jaunt to Jersey. It's unlikely that you'll even cover the whopping eight floors of treatments that this relaxation arena offers, including nine pools, seven sauna rooms, a restaurant and adjoining hotel. But we dare you to try. Among the highlights at this full-service facility are the spectacular rooftop infinity pool, which offers an untouchable view of the NYC skyline; a volcanic sand treatment using rare lava sand imported from Japan; and a scorching charcoal sauna. In summer months, the outdoor pools easily beat the sardine baths of the city, and the indoor saunas will reinvigorate you no matter how brutal the winter gets. There's really no reason to leave when you're in the K-Spa equivalent of Disneyland.