DORNACH FRITH, an arm of the sea on the eastern coast of the Highlands of Scotland, serving as the boundary between the counties of Ross and Sutherland for several miles. It is twelve miles broad at its mouth, and here has more the character of a bay than of a frith. It gradually becomes narrower, till, within three miles west from the town of Dornoch, its breadth decreases to two miles. Above this point it becomes much broader, forming an inner harbour or bay. There are several ferries upon this frith, and near its head it is crossed by an iron bridge, where also the rivers Oykel and Shin empty their waters.