Orkney Islands, archipelago and council area (1991 pop. 19,650), 376 sq mi (974 sq km), N Scotland, consisting of about 70 islands in the Atlantic Ocean and the North Sea, N of Scottish mainland across the Pentland Firth. About 20 islands are inhabited. Mainland (Pomona), the largest, has Kirkwall, the county town, and Stromness. Other large islands are Hoy, South Ronaldsay, Stronsay, Sanday, Westray, and Rousay.
The climate is mild, windy, and wet. The Orkneys are one of Scotland's richest farming regions. Beef cattle and eggs are the most important produce. Sheep and pigs are also raised. Some fishing, mainly for lobster, is carried on. The discovery of North Sea oil in the early 1970s provided employment for many inhabitants.
The Orkney Islands were settled by Picts. Vikings invaded in the 8th cent. From 875 to 1231 it was a Viking earldom under the Norwegian crown. Details of this period are recounted in the Orkneyinga Saga, a Norse epic. In 1231, the islands passed to the Scottish earls of Angus on the death of the last Viking earl. It became a possession of the Scottish crown in 1472 in trust for the undelivered dowry of Margaret of Norway on her marriage to James III (1469), but the Norse occupation left marked Scandinavian traces; islanders spoke Norn (a form of Norse) until the 18th cent. James V visited Kirkwall in 1540 and made the Orkney Islands a county. Scapa Flow, S of Mainland, was Britain's major naval base in World Wars I and II.
The islands have many prehistoric relics. Stone Age villages have been unearthed at Skara Brae on Mainland and a broch (prehistoric fort) at Rinyo on Rousay. Other relics are the burial chambers at Maeshowe and the standing stones at Stenness. The islands have become increasingly popular with tourists and are home to the St. Magnus music festival, founded by the composer Peter Maxwell Davies.