The Kyle of Sutherland is an estuary in the Scottish Highlands formed by the rivers Oykel and Cassley. It extends from the confluence of these rivers to Bonar Bridge, some 16 km downstream, where it widens to become the Dornoch Firth. Along its way, it is joined by the rivers Shin and Carron. It forms part of the traditional boundary between Ross-shire and Sutherland.
