The River Cassley (Scottish Gaelic: Abhainn Charsla, pronounced [au.ɪɲ xaɾs̪ɫ̪ə]) in Sutherland, in northern Scotland, joins the River Oykel to form the Kyle of Sutherland at Invercassley (Inbhir Charsla). The Kyle is subsequently joined by the River Shin and River Carron (Abhainn Charrann) before it becomes the Dornoch Firth and enters the North Sea.