The Volga–Baltic Waterway

This was news to me when I learned of it a few years ago.

The degree to which Europe is blessed by a tremendous inland water-based navigable network --- the Danube, Rhine, and Volga in particular, is hugely underappreciated.

Inland water transport is hands-down the most efficient means of moving large-bulk materials. It's slow, but when measured as mass-distance/hr (tonne-km/hr or ton-mile/hr), net rates of flow are phenomenal. Even where rivers don't meet, the intervening distances are often small, and can be bridged via highway, rail, or canal systems.

The boundaries of most modern European countries can be rougly arrived at by looking at the corresponding watersheds. See:

https://www.visualcapitalist.com/maps-worlds-watersheds/

Especially this map: https://www.visualcapitalist.com/wp-content/uploads/2018/06/...

(I note that well-developed countries tend to have either many useful ports, significant useful waterways, or both, and less-developed ones not so much.)

Russia lacks for warm-water year-round ports, but its inland waterway does link the Mediterranian (via Black Sea) and Baltic seaports. This is in sharp contrast with eastern Russian (Siberia), which largely has south-north flowing rivers which don't reach warm-water ports (Arctic Ocean), or link between river systems.