Alderney, Fr. Aurigny, anc. Riduna, island (1991 pop. 2,297), c.3 sq mi (7.7 sq km), in the English Channel, northernmost of the larger Channel Islands. It is separated from the French coast and from the other islands by swift tidal races. The soil is fertile and well cultivated about St. Anne, the principal town; the island's main crops are potatoes and grains. Tourism is important, as is dairy farming.