[piva00]

That's rather weird, it's one of the most popular summer activities in Stockholm. I personally swim almost everywhere around the city with friends during almost the whole summer, just need to check beforehand on Havs och Vattenmyndigheten daily updates if any bathing areas have been considered inappropriate that day [0].

Most areas are considered appropriate for most of the summer in the inner city, while lakes are everywhere outside the small centre, and quite many are private enough that you can find spots to go skinny dipping without a second thought.

[0] https://www.havochvatten.se/badplatser-och-badvatten/kommune...