Havel , a river of Germany, and the principal right branch of the Elbe. It rises in a small lake near Neu Strelitz in Mecklenburg, flows S., passing within a few miles of Berlin, to Potsdam, and thence W. and N. W. to its junction with the Elbe. Its entire length is 218 m., and it is navigable to Furstenberg, 30 m. from its source. It is the connecting link of a chain of 18 lakes, of which the lake of Tegel, the most northerly, the great lake Between Spandau and Potsdam, the Fahrland-see, the Jungfernsee near Potsdam, and the Schwilowsee are the most important. Near Deetz it expands to a breadth of 1,000 ft., and again contracts suddenly to 300 ft. Near Brandenburg it enlarges into the Beetzsee. Its principal affluents are the Rhin, Dosse, Spree, and Plane. The Finow canal connects it with the Oder, and the Plaue canal with the Elbe; and the Rappin canal, connecting the upper and lower course by means of the Rhin, saves a long stretch of winding navigation. The river, with these canals, is of great importance to the internal commerce of Prussia.