Portmarnock is a coastal suburban settlement in Fingal, Ireland, with significant beaches, a modest commercial core and inland residential estates, and two golf courses, including one of Ireland's best-known golf clubs. As of 2022, the population was 10,750, an increase of 13.5% on the Census 2016 figure of 9,466. Portmarnock is also a civil parish in the ancient barony of Coolock in the traditional County Dublin.