If you wish you could go to an onsen in Japan but can only go as far as below Houston Street in New York, the Shibui Spa at the Greenwich Hotel is almost as good as the real deal. As you enter the subterranean level of the property, it feels like you’ve stumbled across a Narnia-like secret passageway. The indoor pool is beneath a centuries-old reconstructed Japanese farmhouse, and the rooms are trimmed in bamboo. The masseuses here are experts at seeking out knots and kneading them away. Treatments often include onsen soaking rituals to help you relax and sake-soaked hot towels to ease tension.