Europe by geography

The American view of Europe has mainly to do with history and human culture. Old churches, kings and wars, Napoleon and Hitler, the Reinheitsgebot. How about some geography instead? Let us begin by staring at this map of the watersheds of Europe, in which regions are identified by the rivers that carry their rainfall to the sea.

(To pre-empt possible confusion, yes, it's labeled in German: Donau = Danube, etc.)