Tennen Onsen Naniwa-no-Yu (also called Natural Hot Spring Naniwa) is a popular hot spring spa in Osaka. The naturally carbonated mineral waters of the spring are pumped up from 659 meters underground and said to be good for the skin and for several ailments including joint and muscle pain, and general fatigue. Naniwa-no-Yu has both outdoor and indoor baths, saunas, and a massage center. There are six outdoor baths set in a rooftop garden which are particularly enjoyable at night under the stars. Inside there are a variety of hot and cold baths to enjoy, including a powerful jet bath and a micro-nano-bubble bath. Ladies have access to an infra-red sauna, and a salt sauna, and gentlemen can enjoy a dry sauna and a steam sauna.