A waterfall descends from one wall and continues on the floor in the form of a river (projection onto the wall and floor). 
 The wall is made of metal so that artificial stones with magnets can be fixed on it and moved to different places. Water flows around the stones. 
 There are also artificial stones on the floor that change the course of the river. These stones can be moved. There are interactive objects on the projection that can be stepped on while playing with the projection (swimming fish, turtles, etc.). Fish react to humans - they swim to where people walk.