Guernsey is an island in the English Channel off the coast of Normandy that is part of the Bailiwick of Guernsey, a British Crown Dependency.
It is the second largest of the Channel Islands, an island group roughly north of Saint-Malo and west of the Cotentin Peninsula. The jurisdiction consists of ten parishes on the island of Guernsey, three other inhabited islands, and many small islets and rocks.
It is not part of the United Kingdom, although defence and some aspects of international relations are managed by the UK. Although the bailiwicks of Jersey and Guernsey are often referred to collectively as the Channel Islands, the "Channel Islands" are not a constitutional or political unit.
Wikipedia https://en.wikipedia.org/wiki/Guernsey
Koordinaten 49°27'24.531" N -2°32'20.393" E