SPA Amenity is a term used to describe the various amenities offered at a SPA. These amenities can include a SAUNA, ROBE, and hot tub. A SAUNA is a small room or house designed as a place to experience dry or wet heat sessions, or an atmosphere with high humidity. A ROBE is a loose-fitting outer garment typically worn after bathing or other activities. A hot tub is a large tub or small pool of heated water used for relaxation or hydrotherapy.