Sissle

The Sissle (Swiss German, ) is a long river in the Swiss canton of Aargau in Switzerland. It is a tributary of the Rhine and drains the eastern part of the Fricktal. The largest town on the river is Frick.

The river rises in the municipalities of Schinznach-Dorf and Thalheim at an elevation of above sea level on the southern slope of Mount Dreierberg and the northern slope of Mount Zeiher Homberg, in the Jura Mountains. Shortly after the source, the river breaks through a water gap between the Dreierberg mountain and the Zeiher Homberg and then falls off rapidly. It passed the Talmatt and delimits the district Iberg of the municipality of Zeihen. After about , the Sissle flows past Effingen railway station and the west portal of the Bözberg railway tunnel, at an elevation of about . The river had to be canalized here when the railway was constructed.