Pentland Firth
a channel between the Atlantic and German Oceans, separating the mainland of Scotland from the Orkney Islands. It is 14 miles long and 64 miles broad at the narrowest. The Pentland Skerries, 5 miles N. E. of Duncansbay Head, consists of two islets and of several contiguous rocks.
On the larger of the islets is a lighthouse (1794). Although navigation of the Pentland Firth is more dangerous than that of any other portion of the Scotch seas, over 5,000 vessels with cargoes pass through the Firth annually.