Sestroretsk (Russian: Сестроре́цк; Finnish: Siestarjoki; Swedish: Systerbäck) is a municipal town in Kurortny District of the federal city of St. Petersburg, Russia, located on the shores of the Gulf of Finland, the Sestra River and the Sestroretskiy Lake 34 kilometers (21 mi) northwest of St. Petersburg. Population: 37,248 (2010 Census); 40,287 (2002 Census); 35,498 (1989 Census); 30,500 (1975).