The Yrjönkatu swimming hall in Helsinki (named after the street, Yrjö = George, katu = street) is a wonderful 1920's place, relaxed, occasionally cruisy, and usually closed for the summer:
Yrjönkatu Swimming Hall | My Helsinki. In the summer time there's a really fun outdoor swimming pool next to the Olympic stadium. Segregated men's sauna. Nudity in Finland is very natural as there's a 2000+ year tradition with sauna, and sauna as a word is of Finnish language. In a country with 5,8 million inhabitants, there are 3,5 million saunas. You bathe nude as a family. When boys and girls reach puberty, the segregation starts to occur, but it's not that tight. There's an island off the Helsinki harbor called Pihlajasaari that has a nice nude beach. It's a 10-minute boat ride there, cafes and a restaurant on the island.