The Dobra is a river located mostly in the Karlovac County in the Republic of Croatia. It is 104 kilometres (65 mi) long and its basin covers an area of 900 square kilometres (350 sq mi). Its name is the feminine form of the Croatian adjective meaning "good" but it is over simplistic folk etymology. The river name probably comes from the Celticdubrum, dubron meaning ‘water’, Illyrian δυβρις (dybris) ‘deep’ or Old Slavonic dъbrь (Dubri, debra) also ‘deep’ or ‘valley’.
Dobra rises in Gorski Kotar near Skrad and Ravna Gora, where it flows first to the north and then turns to the east. It flows past Vrbovsko, to the southeast into the city of Ogulin, where it becomes an underground stream. It takes a sharp northward turn and rises back to the surface north of Ogulin. It continues to the northeast, past the Lešće spa and a hydroelectric plant (built and in test operation as of 2010[update]), running in parallel to the Kupa and Mrežnica, and finally flows into the Kupa north of Karlovac.