In the former class are the Isere, the Rhone, the Aar, the Ticino, the Tosa, the Hinter (or main) Rhine and the Linth; while in the latter class we have the Durance, the Po, the Reuss, the Vorder and middle branches of the Rhine, the Inn, the Adda, the Oglio and the Adige.
The route quits that of the Albula Pass at Thusis, passes first through the celebrated gorge of the Via Mala, then through the Schams basin and past Andeer, beyond which the Rofna gorge gives access to the village of Sphigen (from which the pass takes its name) in the upper reach of the main or Hinter branch of the Rhine.
Starting from Coire the Rhine valley is followed to Reichenau (6 1/.4 m.), and then that of the Hinter Rhine to Thusis (10 1/2 m.).