Which is the longest river that flows through the most countries?

The Danube

The Danube, a true cultural and historical crossroads of Europe, flows through more countries than any other river in the world. From its source in Germany to its delta in the Black Sea, it unites diverse nations, fostering trade, culture, and dialogue. Its basin is a biodiversity hotspot, hosting unique species. The Danube is also at the heart of international efforts for conservation and sustainable development, demonstrating how natural resources can bring peoples and countries together in a common goal of preservation and prosperity.