There are swimmingpools and then there is the Liljeholmsbadet. It's a floating swimmingpool and by far the best place to swim indoors in Stockholm. The water temperature was 24ºC, the water is crystal clear and it has the old world charm (when swimming was still elegant). I heard of this pool from a local after a disasterous visit to the Storkyrkanbadet in gamla stan (briefly: I was chased around the pool by a lunatic - apparently everybody knows him and he is considered harmless and probably just wanted to say hi - but how should visitors know this?).