Beloostrov (ru|Белоо́стров; fi|Valkeasaari;), from 1922 to World War II Krasnoostrov (ru|Красноо́стров|lit=Red Island|link=no), is a municipal settlement in Kurortny District of the federal city of St. Petersburg, Russia, located on the Sestra River, Karelian Isthmus. Population: The settlement has a railway station Beloostrov.
Beloostrov historically consists of two parts: Novy Beloostrov (ru|Но́вый Белоо́стров, New White Island; fi|Uusi Valkeasaari) along the railway and Stary Beloostrov (ru|Ста́рый Белоо́стров, Old White Island; fi|Vanha Valkeasaari) several kilometers to the north, mostly belonging to Vsevolozhsky District of Leningrad Oblast under the name Sadovodstva Island (ru|остров Садоводства). Until the Winter War Beloostrov was the last railway station before the Russia–Finland border.
Beloostrov has been a key station of the Saint Petersburg-Vyborg railroad since 1870 (initially named Rayala (fi|Rajala)) at the junction of Saint Petersburg–Zelenogorsk and Saint Petersburg–Sestroretsk–Beloostrov sections, being the final destination of many suburban passenger electric trains from the Finland Railroad Station.