Naked? With strangers? This is how you relax in the spa in Europe. In Austria and Germany there are many popular spas called thermen.
Walk in in a swimsuit and you'll get stares and maybe even reprimands. For some Americans, including children, aufguss is prohibited, where all clothing, including swimsuits, is not allowed in the saunas, where nudity is required. For residents of German-speaking countries, it is a very popular pastime, especially in autumn and winter.