The Little Brosna River is a historic and beloved angling destination flowing through the Irish Midlands, beginning its journey near Dunkerrin in County Offaly and traveling approximately 57.6 kilometers (35.8 miles) before joining the River Shannon. Along much of its course, the river forms the natural border between County Offaly and County Tipperary, passing through the town of Birr and draining a basin of roughly 662 square kilometers. With an average discharge of around 8 cubic meters per second, the Little Brosna is a productive, well-established trout and salmon fishery that draws both local and visiting anglers, contributing significantly to the tourism economy of the region. The river is particularly celebrated for its population of wild brown trout, including the remarkable croneen — a migratory brown trout that travels from Lough Derg upstream to spawn in the Little Brosna and its tributaries. The river's riparian corridor supports rich biodiversity, including the increasingly rare white-clawed crayfish, otters, and internationally important wetland habitats such as the Little Brosna Callows.