Mixed nude beaches might be on the decline, but mixed nude spas certainly aren't. New ones are popping up in the Germany/Netherlands/Belgium region every day.

Mixed nude beaches might be on the decline, but mixed nude spas certainly aren't. New ones are popping up in the Germany/Netherlands/Belgium region every day. Japan is a bit different when it comes to baths. Traditionally many Japanese homes didn't have a bath, public baths remained popular far longer than they did in Europe. Having free hot (volcanic) water available also helps, which I guess is easier to exploit in a large onsen than it is at home. Also, they do have mixed onsen, but those are pretty rare (these days?).