Regen River

Infobox River
river_name = Regen


caption = The Regen near Lappersdorf.
origin = Bohemian Forest
mouth = Danube
basin_countries = Germany, Czech Republic
length = 169 km
elevation =
discharge = 40 m³/s
watershed = 2,953 km²The Regen ( _cs. Řezná) is a river in Bavaria, Germany, a left tributary of the Danube. The source of its main headstream, the "Großer Regen" ("Big Regen"), is located in the Bohemian Forest on the territory of the Czech Republic, near Železná Ruda. The river crosses the border after a few kilometres, at Bayerisch Eisenstein.

At Zwiesel, the "Großer Regen" is joined by the "Kleiner Regen" ("Little Regen") to form the "Schwarzer Regen" ("Black Regen"). The "Schwarzer Regen" flows through Regen and Viechtach, and is joined by the "Weißer Regen" ("White Regen") in Kötzting. From this confluence, the river is called Regen.

The Regen Valley forms the main valley crossing the Bavarian Forest; many settlements within the mountains are located along the river. Cities along the Regen river include Cham and Regensburg. At Regensburg the river joins the Danube.

The river's total length, including its headstreams "Großer Regen" and "Schwarzer Regen", is 169 km.