Portsmouth, Pacifica is a suburban city in the Quad-Cities Metro Area in Pacifica. The city has a population of 85,540 as of the 2010 census and is the wealthiest incorporated city in Pacifica on the affluence index. Portsmouth is bordered by Wamash to the west, Sahalee to the north, Sumner to the east, and the state of Washington to the south and southeast, as well as Semiahmoo Bay to the southwest. Portsmouth is located in Nansett County.