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
Baltic Ice Lake small channel in the Strait of Øresund. The lake was higher than sea level (which itself was lower than the present-day sea level) by some tens of metres. Lake Ladoga was part of it. Emergence of the land then closed the channel through the Strait of Öresund. The lake rose until at about 11,200 BP it broke through a narrow corridor in the region of Mount Billingen in present-day south-west Sweden; this used to be described by Quaternary geologists as a massive, single tap of Niagara-like force but it is now considered more likely that it happened in several steps