Alderney is the northernmost of the inhabited Channel Islands. It is part of the Bailiwick of Guernsey, a British Crown dependency. It is 3 miles long and 1 1/2 miles wide.
The area is 3 square miles, making it the third-largest island of the Channel Islands, and the second largest in the Bailiwick. It is around 10 miles from the west of La Hague on the Cotentin Peninsula, Normandy, in France, 20 miles from the north-east of Guernsey and 60 miles from the south coast of Great Britain. It is the closest of the Channel Islands to both France and the United Kingdom. It is separated from Cap de la Hague by the dangerous Alderney Race.