The lighthouse tower is listed as a building of Architectural/Historical interest. Pentland Skerries (Muckle Skerry) The Pentland Skerries (Old Norse: Pettlandssker [1]) are a group of four uninhabited islands lying in the Pentland Firth, northeast of Duncansby Head and south of South Ronaldsay in Scotland. The lighthouse is located on Muckle Skerry, the largest of the group, about 8 km northeast of Duncansby Head on the mainland and 6 km south of Brough Ness, South Ronaldsay, in the Orkney Isles. The lighthouse tower is listed as a building of Architectural/Historical interest. The islets consist of Muckle Skerry and a long shoal running northeast from Little Skerry to Clettack Skerry. The Pentland Skerries are small rocky islands obstructing the eastern entrance to Pentland Firth. Pentland Skerries Lighthouse. By far the largest of the islands is Muckle Skerry, home to … History. The Pentland Skerries is a small group of islets, stacks and reefs located in the Pentland Firth that separates the Scottish mainland from Orkney. Pentland Skerries Lighthouse was established in 1794 by T Smith and Robert Stevenson.