The Rench is a right-hand tributary of the Rhine in the Ortenau. It rises on the southern edge of the Northern Black Forest at Kniebis near Bad Griesbach im Schwarzwald. The source farthest from the mouth is that of the Schöngrundbächle which rises at a height of around 915 m above NN in the parish of Zuflucht near the old youth hostel. After flowing through its steep mountainside klinge it is joined by other streams to form, first, the Old (Alter), then the Wild Rench, which first becomes the Rench below Bad Griesbach. The Rench runs in a prominent southerly arc through the Central Black Forest and crosses the hilly region of Ortenau with its orchards and vineyards before breaking out into the Rhine Plain. After just under 57 km it discharges, together with the Mühlbach, into the Rhine at 314.7 km between Helmlingen (Rheinau) and Lichtenau.