The Danube River flows through several countries in Europe including Germany, Austria, Hungary, and Romania. It is the second-longest river in Europe, measuring about 2,850 kilometers. The Danube is crucial for navigation, trade, and as a water source for millions of people. Its basin supports diverse ecosystems and cultural heritage, with numerous cities along its banks, such as Budapest and Vienna. The river has historically served as a vital trade route, connecting various cultures and economies across the continent.