The Saint Petersburg Metro is the underground railway system in Saint Petersburg and Leningrad Oblast, Russia.
Due to the city's unique geology, the Saint Petersburg Metro is one of the deepest subway systems in the world and the deepest by the average depth of all the stations. The system's deepest station, Admiralteyskaya, is 105 metres below ground. Serving nearly three million passengers daily, it is also the 13th busiest subway system in the world.