Carrickfergus (kărˌĭkfûrˈgəs) [key], town (1991 pop. 19,100) and district, E Northern Ireland, on the shore of Belfast Lough. A minor fishing port, the town has die-casting, distribution, electronics, and energy and mineral industries. A castle and church built in the 12th cent. still stand. John Paul Jones fought (1778) a victorious battle offshore from Carrickfergus. The area is a center for leisure boating and is known for its scenic camping and hiking.