Portumna is a market town in the south-east of County Galway, Ireland, on the border with and linked by a bridge to County Tipperary. The town is located to the west of the point where the River Shannon enters Lough Derg. This historic crossing point over the River Shannon between counties Tipperary and Galway has a long history of bridges and ferry crossings. On the south-western edge of the town lie Portumna Castle and Portumna forest park.