The Berounka () is a river in the Czech Republic, a left tributary of the Vltava River. It flows through the Plzeà  and Central Bohemian regions to Prague. It is formed by the confluence of the Mà ¾e and Radbuza rivers in Plzeà Â. Together with the Mà ¾e, which is its main source, the Berounka is long, which makes it the fifth longest river in the Czech Republic. Without the Mà ¾e, it is long.
The river is named after the town of Beroun. Originally, the entire stream was called Mà ¾e () and the name first appeared in the 12th century, among others in Chronica Boemorum. The name was written as Mse, Msa and Misa. From the 17th century, the lower course started to be named Berounka, but the name Mà ¾e still appeared as a name for the entire stream at the end of the 19th century. In order to avoid confusion, an initiative to rename the lower course back to the historical name Mà ¾e was created in 2008, but its efforts were unsuccessful due to the strongly adopted current name.
From a water management point of view, the Berounka and Mà ¾e are two different rivers with separate numbering of river kilometres. In a broader point of view, the Berounka (as Mà ¾e) originates in the territory of Mähring in the Upper Palatine Forest at an elevation of and flows to Prague-Lahovice, where it enters the Vltava River at an elevation of . It is long, of which is in Germany. In the Czech Republic, it is long, which makes it the fifth longest river in the country. Its drainage basin has an area of . The name Berounka is used from the confluence of the Mà ¾e with the Radbuza in Plzeà  and from this point to the confluence with the Vltava, the river is long.
The Berounka has many significant tributaries. The sources and longest tributaries of the Berounka are:
There are several large settlements on the river. The Mà ¾e flows through Tachov and Stà ÂÃÂbro. After its confluence with the Radbuza in Plzeà Â, the Berounka flows through Beroun, à Âevnice, Dobà Âichovice, ÃÂernoà ¡ice and along the edge of Prague.
There are 7,502 bodies of water in the basin area; the largest of them is the Hracholusky Reservoir with an area of , built at the confluence of the Mà ¾e and the stream ÃÂterský potok. There are no bodies of water built directly on the lower course of the Berounka.
The river is home to the mollusc Unio pictorum, which is critically endangered within the Czech Republic. The endemic species Bulgarica nitidosa lives by the river.
There is an artificial slalom course in Roztoky, on the 63rd river km.
The Berounka is considered one of the most beautiful rivers in the country and is among the most popular rivers for river tourism. Almost its entire flow from Plzeà  is navigable. It is popular thanks to the sections in the protected landscape areas of Kà Âivoklátsko and ÃÂeský kras, which lead through unspoiled nature. The Berounka belongs to the undemanding rivers suitable for beginner paddlers. An 82 km long educational trail for paddlers runs along the river.