Overview
Forss Water, known also as Forss River, has its source at the northern end of Loch Shurrey, at . About 13 kilometres north of its source the river flows into Crosskirk Bay and the Atlantic Ocean at . Crosskirk Bay is on the north coast of Great Britain and about 8 kilometres west of the burgh of Thurso, Caithness, in Highland, Scotland. The river marked the eastern extent of the Clan Mackay raid in the Sandside Chase of 1437.
Tributaries
* Alt Torigil, known also as Alt Forsiescye, enters the river at . * Alltan Guinne enters at . * The Burn of Baillie enters at . * The Burn of Brimside enters at .
Bridges
The river is crossed by four road bridges and one footbridge. The road bridges are: * Near the river's source at Loch Shurrey, at . * Near Broubster Village, at . * Near Westfield, at . * Near Lythmore, at . * The Bridge of Forss, which carries the A836 road at . The A836 leads towards Thurso and John o' Groats in the east and towards Reay, Melvich, Bettyhill and Tongue in the west. The footbridge is near the river's mouth at , providing access to St Marys Chapel, to the west of the river, from Crosskirk, to the east.