If you’ve ever been tempted to splash into Rome's Trevi Fountain sans clothing or skinny-dip under a Grecian sky, this superspa in Osaka is just the spot for you. Part centuries-old tradition, part Disney-esque water park, Spa World (www.spaworld.co.jp) is Japan’s most lavish and popular onsen, which, by Western standards, is like a combination of a spa and hot springs. Its multiple levels of baths feature clothing-free levels, one with an Asian theme and the other European, which alternate every month for male and female bathers. Sections are arranged by countries, complete with iconic landmarks (like the Trevi Fountain). According to onsen etiquette, the soaker should wash thoroughly before entering the male or female area. Towels are used while walking from one area to another, though they’re more appropriately sized for locals instead of more robust Westerners. And if you’ve got body ink, may be out of luck, as tattoos, whether permanent or temporary, are usually prohibited.

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