The Vydra (Czech for "otter", German: Widra) is a 23.1 kilometres (14.4 mi) river in the Czech Republic.
The Vydra begins in the Bohemian Forest near Modrava, at the confluence of the Roklanský potok and the Modravský potok. However, Modravský potok's tributary, the Luzenský potok originates slightly across the Germany–Czech Republic border 1,215 metres (3,986 ft) up the north slopes of Mt. Lusen Czech: Luzný) in Bavaria is considered to be the Vydra's true source.
From Modrava, the Vydra flows northward and merges with the Křemelná west of Svojše to form the Otava.
Coordinates: 49°06′N 13°30′E / 49.100°N 13.500°E