Shetland Islands, archipelago, 552 sq mi (1,427 sq km), off N Scotland. They consist of c.100 islands c.70 mi (110 km) long, about a fourth of which are inhabited. The largest are Mainland (where Lerwick, the main town, is located), Yell, Unst, Fetlar, Whalsey, and Bressay. Oil, produced offshore in the North Sea since the 1970s, supplements income
from traditional sheep, cattle, and knitware industries. Tourism is also important. The hardy Shetland pony and the Shetland sheepdog originated there. Occupied by Norsemen by the 9th cent., the islands were annexed to Scotland in 1472.