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.

Fingal is a county in Ireland. It is in the province of Leinster and is part of the Eastern and Midland Region. It is one of three successor counties to County Dublin, which was disestablished for administrative purposes in 1994. Its name is derived from the medieval territory of Scandinavian foreigners that settled in the area. Fingal County Council is the local authority for the county. In 2022 the population of the county was 330,506, making it the second most populated council in Dublin and the third most populous county in the state.