The bathing season in Berlin started May 1st and one of the most unusually outdoors pools is the so called bath ship (Badeschiff)

 

You can find the web site of the Badeschiff here.  Here you can also find a video which shows, how they're turning it into a sauna in the winter.

Very close to the Badeschiff at the same area is „Club der Visionäre“, where one you can sit on wooden Pontons, listen to DJ's, put your legs into the water, have beer with friends - gorgeous place!

And for people who like a it a little more quiet there is also the Boat Restaurant Freischimmer where you can have your beer or bionade 2 feets above the water. There are not many place like this to stay on a warm summer afternoon.

Did I mention that all of these place are less then 10 min walking distance form out berlin19?