Eighteen naked women and girls are sitting in a 14-by-12-foot pine-walled room in the basement of the Finnish embassy on a wintry Saturday night. It's 200 degrees in here, and everyone's sweating profusely, the heat amplified each time someone ladles more water onto a large rock-topped heater. The sensation is something like Washington in August, times 2. "My skin feels like velvet," coos an older woman as perspiration trickles down her chest. Others close their eyes, quiet and blissful, in the steamy, dimly lighted sauna.

These women are members of the Finlandia Foundation -- 90 or so local Finns and Finnophiles and their kids -- who are borrowing the embassy's facilities on Massachusetts Avenue for their annual sauna night celebration. The men and women switch places every hour of the four-hour sweatfest, taking turns in the sauna, then showering and dressing casually for a party set up on the modern, glass-walled ground floor. That's where, in shifts, everyone drinks beer and picks from a potluck spread that includes kielbasa speared with little Finnish flags (the kielbasa represents sauna makkara, a traditional sausage cooked on sauna stones), fruit and a heavy dose of potato casseroles. The good-natured consensus around the buffet seems to be that Americans don't really "get" the sauna ("SOW-na," rhyming with "COW-na," not "SAW-na"), which holds such a central place in Finnish culture that people often hold business meetings in them.

"In Finland, you say, 'Come on over; we'll take a sauna,' " says expat Anna-Mari Barrineau, who has been in the United States for 20 years now and has a sauna at her home in Burke. "I'm starting to see how crazy that sounds here. It's like, 'Come on over; we'll take a shower together!' "

But, adds another Finn, Liisa Herweg, 65, of Fairfax, "There's absolutely nothing sexual about sauna. It's too hot, first of all . . ."

Barrineau, who's president of the foundation, and Herweg sit before plates heavy with sausage. They're next to Erik Lindstrom, 79, a Finn with a sauna-construction business in Port Tobacco who helped build the embassy's sauna in the mid-'90s. Lindstrom, whose license plate reads "I SAUNA," believes that the sauna's benefits are myriad: It lowers stress, flushes out toxins, relieves congestion, burns calories. He's a bit weepy tonight, though, in part because an accordionist named Vic Aijala is playing old Finnish standards, reminding him of his homeland. "Maybe I can quit crying if he quits playing," he says.

Some of the women start heading back down to the sauna at 8 o'clock, as the men come up for beer. Before entering the sauna, Herweg and a few other women guzzle glasses of water (as a CD plays "Itsy Bitsy Teeny Weeny Yellow Polka Dot Bikini" in Finnish), undress and shower before entering with towels to sit on. They stay for 10 or 15 minutes, shower, then return to the buffet.

The guys are different, says Merry Bruns, 51, a cheerful Web site-content strategist who lives in Chevy Chase and whose grandparents came to the West Coast from Finland years ago. "Men don't take care of each other like we do. We say, 'Are you all right? Do you need water?' Guys tough it out. They're idiots."

Bruns's husband, who doesn't want his name published, has fainted twice at past sauna nights because he stayed and sweltered for nearly a full hour both times. "It's a testosterone thing," he says tonight, with a grin, before heading down for what he promised would be a shorter time. "For women, it's a social event," he explains. "It's a chance to chat with your friends. But on the male side, it's a competition" for who can take the most heat.

Later, downstairs and back in the sauna, Herweg says that in Finland, traditionally, "the idea is that it's a stress reliever, so you need to quiet down -- it's like a church." There's chitchat all around her, she concedes, but this is America. "You can talk in Finland but not chatter," she adds. "Sauna is sacred."

>>If you have an upcoming party you'd like to share, e-mail us at partyanimal@washpost.com.