The River Thurso (Scottish Gaelic: Abhainn Theòrsa) has Loch Rumsdale in Caithness as its source, about 26 kilometres south and 14 kilometres west of the burgh of Thurso, Caithness, and about 2 kilometres south of the railway line linking the burghs of Thurso and Wick with Inverness. At its source and until it reaches Loch More the river is known also as Strathmore Water.