|⁃ location||near Poddubye village|
|⁃ elevation||60 m (200 ft)|
|Length||121 km (75 mi)|
|Basin size||1,640 km2 (630 sq mi)|
Tosna River (Russian: То́сна) is a river in Luzhsky, Tosnensky, and Kirovsky Districts of Leningrad Oblast, Russia, as well as in the city of Saint Petersburg. It is a left tributary of Neva River. The towns of Tosno, Nikolskoye, and Otradnoye, as well as the urban-type settlement of Ulyanovka are located along the Tosna. The length of the Tosna is 121 kilometres (75 mi), and the area of its drainage basin is 1,640 square kilometres (630 sq mi). The main tributary of the river is the Yeglinka (left).
The source of the Tosna lies in swamps south of the settlement of Radofinnikovo. The river flows north, enters Tosnensky District, passes the town of Tosno, and essentially enters the suburbs of Saint Petersburg. There, it flows through Ulyanovka and Nikolskoye. In this area, limestone rocks occasionally form the banks of the Tosna. In particular, Sablinskiye Caves, disused quarries, are located by the river. A stretch of Tosna between Nikolskoye and Otradnoye serves as a border between the city of Saint Petersburg (west) and Leningrad Oblast (east). The mouth of the Tosna is located in the town of Otradnoye.
The river basin of the Tosna includes the western part of Tosnensky District, as well as minor areas in Luzhsky and Kirovsky Districts and in the city of Saint Petersburg.