Guernsey, second largest of the Channel Islands. It is 30 miles (48 km) west of Normandy, France, and roughly triangular in shape. With Alderney, Sark, Herm, Jethou, and associated islets, it forms the Bailiwick of Guernsey. Its capital is St. Peter Port. Guernsey ceased to be ruled by Normandy in 1204.