The
Hinterrhein (, ) is one of the two initial
tributaries of the
Rhine (less in length but bigger by volume) in the
canton of
Graubünden in
Switzerland, flowing from the village
Hinterrhein near the
San Bernardino Pass through the
Rheinwald valley into a gorge called
Roflaschlucht. In this gorge an equally sized tributary, the
Avers Rhine, adds waters from the deep
Val Ferrera and the very remote
alp Avers and its side valley
Valle di Lei on Italian territory. After the
Rofla Gorge, the valley widens into a section called
Schams. The Hinterrhein then reaches
Andeer, before passing through another gorge,
Viamala just before
Thusis. Now another tributary of slightly bigger volume reaches the Hinterrhein as the
Landwasser, draining a system of valleys, which is commonly known as
Davos joins via the
Albula coming from the
Albula Pass, which is also the name of a railway line that has become a
UNESCO world heritage. Another big tributary of Albula river is
Gelgia from the
Julier pass area. After flowing to Rothenbrunnen through a valley called
Domleschg with an incredible number of castles (showing the importance of transit in the area) again the river is left alone from civilisation in the
floodplain Isla Bella near
Rhäzüns, before it joins the
Anterior Rhine at
Reichenau, all of them also in Graubünden.