Santas in the water - "Samichlausschwimmen"
A very funny and frosty tradition in Zurich is called Samichlausschwimmen, that can be translated as Santa Claus swimming.
Since 2000 a group of friends decided to have a swim in the wintry Limmat in Santa Claus costumes. From year to year more participants joined to this challenge, some of them say it's good for their health. But since 2011 it is definitely good for your soul, as the proceeds of the event are donated for charity.
A chilling experience for swimmers and spectators as well. See the whole program here (available in German).