Which is the longest river between the elbe Danube Rhine seine and tagus?

The longest river among the Elbe, Danube, Rhine, Seine, and Tagus is the Danube. It stretches about 2,860 kilometers (1,777 miles) through Central and Eastern Europe, flowing through multiple countries before emptying into the Black Sea. The Elbe is approximately 1,091 kilometers (678 miles), the Rhine is about 1,233 kilometers (768 miles), the Seine is around 777 kilometers (483 miles), and the Tagus measures about 1,007 kilometers (626 miles).