On every 1st and 3rd Sunday of a month can be swum from 10 am to 1 pm with mermaid costumes in the pool Westbad Freiburg.
If you do not have your own costume yet, you can borrow one there and try it out for half an hour for about 3.50 ?!! A pre-registration is not necessary here.
Often more than 100 mermaids have fun there!!
Here is the link: Westbad