Leningrad Oblast of two great lakes of the European Part of Russia, Lake Ladoga and Lake Onega. Its northeastern part, between the Gulf of Finland and Lake Ladoga, occupies the Karelian Isthmus. Some islands in the Gulf of Finland (including Kotlin, on which the city of Kronstadt has been built) and Lake Ladoga (including Konevets) also belong to the oblast. Much of the area of the oblast belongs to the drainage basin of the Neva, which is the only outflow of Lake Ladoga. Whereas the Neva, which flows to the Gulf of Finland (the city of Saint Petersburg is located in its
Lake Komsomolskoye the Lake Ladoga depression, a graben and syncline structure of Proterozoic age (Precambrian). Deglaciation following the Weichsel glaciation took place in the Lake Ladoga basin between 12,500 and 11,500 radiocarbon years BP. During the existence of Lake Komsomolskoye there have been three sharp drops in the water level, so that the shore consists of small but distinctive terraces formed on the banks. The shores of the lake are indented with several bays and inlets, overgrown with sedges and reeds. On the south-eastern shore of the lake is the village of . At the northern extremity of the lake are the