The Riedberg Pass is with 1407 m above sea level. NHN [1] the highest passable mountain pass in Germany. It is located near the eponymous Riedberger Horn (1787 m) in the Allgäu Alps on the county road OA 9 between Obermaiselstein and Balderschwang in the Bavarian district Oberallgäu.
Riedberger Horn, located northwest of the Riedberg Pass, and the Schafkopf, located south of the pass, runs along the Rhine-Danube watershed, which is part of the main European watershed:
The water of the (western) Bolgenach, which rises 3.8 km south-southeast of the Riedberg Horn and 1.9 km south of the pass at the southern foot of the Schafkopf, reaches through the Weißach, the Bregenzer Ach, Lake Constance and the Rhine in predominantly northwest direction North Sea.
Accordingly, the water runs the hamlet Ach, the 4.4 km east-northeast from their two source streams, the left (eastern) Bolgenach and the right, a few meters west past the pass flowing Schönberger Ach, through the Iller and the Danube in mainly east-southeastern direction in the Black Sea; the source creeks spring north or south of the ridge near the pass between Riedberger Horn in the west and Wannenkopf in the east.
Source: Wikipedia