The River Dun, also known as the Glendun River (in Irish: Abhann Duinne, brown river) is a river in County Antrim, Northern Ireland. It runs through Glendun, one of the nine Glens of Antrim. The river is named after its brown colour, which comes from the peat bogs at its source on the slopes of Slievenanee on the Antrim Plateau. The source of the river is a few hundred metres from that of the River Bush, which flows north-east to meet the sea at Bushmills.