Although it is shorter in length, its volume is larger than that of the Vorderrhein at their confluence near Reichenau, after which the river is called the Alpine Rhine, which flows out into Lake Constance (Bodensee).

The two main tributaries of the Albula are the Landwasser, flowing through Davos, and the Gelgia from the Julier pass area.

After passing Rothenbrunnen through a valley called Domleschg (a valley with an incredible number of castles, showing the importance of transit in the area) the Hinterrhein is again left alone from civilisation in the floodplain Isla Bella near Rhäzüns, before it joins the Anterior Rhine (Vorderrhein) at Reichenau, near Bonaduz.

The drainage basin of the Hinterrhein lies mostly within the canton of Grisons, with one tributary, the Reno di Lei rising in Lombardy, Italy (Sondrio).

The nearby Lunghin Pass is the triple divide between the rivers Rhine, Danube and Po.