The Danube flows through more countries than any other river in Europe.

The longer version

Rivers ignore political borders, following gravity instead. A long river that begins in a mountainous region and crosses a broad plain is likely to pass through many states before reaching the sea. This one starts in a central European highland and travels east and south to a delta on the Black Sea.

Each country along the way uses the water for transport, power and irrigation, so shared agreements govern navigation and pollution. The delta forms a wetland of international importance for birds. Tributaries add flow along the route, making the lower river much wider than the upper one.

Where this entry sits

These facts wander across maps, borders, deserts, rivers, mountains, and the extreme corners of the natural world. Each one is short and self-contained, offering a small surprise about places you may never visit rather than anything you actually need. The full list sits on the Geography page, where every entry is listed in order.