Gin no Yu, Kobe

Best Onsen in Japan in terms of uniqueness of the water. The red water is filled with iron minerals. It’s a bit hot (above 41 C). Come with your own towel or pay ¥200 extra. Have some local milk or local cider after your bath.

For a public Onsen it's perfectly pleasant. I'd recommend arriving late or early or you will be quiet for up to an hour l. Inside is very rustic and authentic and the staff will guide you if you can't figure out what to do. It's three baths of vetting temperatures. My only gripe is it's a little small and has no outside bathing, but some people might prefer that. You can also pick up a local beer and the famous cider water after which are both very tasty !