Kyle of Sutherland is a river estuary that separates Sutherland from Ross-shire. It flows into the Dornoch Firth and is fed by the rivers Oykel, Shin, River Cassley and Carron.
The downstream extent[1] of the Kyle of Sutherland is the bridge at Bonar Bridge. The upstream end of 'the Kyle' as it is locally known is the furthest inland extent of tidal water[2], which corresponds to 'the bailey bridge', beyond Rosehall.
The Kyle did separate Sutherland-shire and Ross-shire for centuries until 1975[3][4] when The Highland Region reorganised its internal boundaries leaving both banks within Sutherland.