Amherst Island (22.8 sq mi/59.1 sq km), SE Ont., Canada, one of the Thousand Isls., at head of L. Ontario, near entrance to the St. Lawrence, 7 mi/11 km WSW of Kingston; 11 mi/18 km long, 5 mi/8 km wide; 44°08'N 76°43'W. Popular resort. Granted to La Salle by Louis XIV; originally called Île de Tonti.