The Rienza starts in the Sexten Dolomites, threads through Lake Dobbiaco, and then does the long work of draining the whole Val Pusteria — the better part of eighty kilometres — picking up the Aurino near Bruneck along the way before it finally hands itself over to the Isarco at Bressanone. It's a proper valley river by the lower stretches: wide enough to need thinking about, with long flat glides between the pools where dry fly work rewards patience more than accuracy. The geology shifts as you move downstream, dolomite limestone at the source giving way to the granite and gneiss along the main Periadriatic fault line, and the water's character shifts with it. Brown trout, marble trout, the odd hybrid, and grayling all hold here, in numbers good enough that local guides rate it among the best all-round fisheries in South Tyrol. Nymph and streamer work through most of the year; the dry fly comes into its own on the long flats once the water clears and settles.

• Mixed