Had I ever seen so much bare flesh in one room? Naked in a mixed-gender Austrian sauna, I sat opposite two dozen other nude people on wooden benches. Even after more than a year of living in Europe, as an American, I still felt a little uncomfortable sitting there in nothing but my own skin.

The sauna master came in to warm things up. Tall and lanky, wearing just a towel wrapped around his hips, he wheeled in a cart with several grapefruit-size balls of crushed ice infused with essential oils like black pepper, lime and eucalyptus. After a short speech telling us to leave immediately if we felt dizzy, he placed one of the ice balls onto a tray of hot coals, and it began to sizzle. The smell reminded me of an expensive aromatic candle: a touch sweet, a touch spicy.

He twisted forward, backward and sideways with a large towel clutched between his hands, like a half-dressed matador, moving the air around the room with a singular goal: to get us very, very hot, as part of a sauna ritual called aufguss, German for “infusion.” As I watched, mesmerized, I began to forget my awkwardness — or that I was even naked.

No swimsuits allowed

Austria and Germany abound with spas called thermen — resorts with pools, saunas, lakes, restaurants, bars and treatment areas. Typically, they have a warm mineral spring, and a section where nudity is required. Walk in wearing swim trunks and you’ll get glares and maybe even reprimands.

I had traveled to St. Martins Therme & Lodge in Frauenkirchen, a small town about an hour southeast of Vienna. St. Martins stands next to a serene, shallow lake where guests can swim in the summer or take a cold plunge in winter. At the center of the therme is an atrium with a pool that has indoor and outdoor areas connected via a tunnel, floor-to-ceiling windows that look out onto the lake and several levels of balconies with rows of lounge chairs. The complex has five saunas and a steam room; 11 thermal pools; a treatment area with massages, facials and more; a restaurant; and a cafe. A day pass is 53 euros, or about $58.