Saint Petersburg Dam, Flood control dam in Saint Petersburg, Russia.

The Saint Petersburg Dam runs 25.4 km across the Gulf of Finland from Bronka through Kotlin Island, where Kronstadt stands, to Gorskaya near Sestroretsk. It consists of 11 earth-and-stone dams, six water-passage structures with segment gates, and two ship locks: S-1 with a 200 m span and floating caissons, and S-2 with a 110 m span and a 2,500-tonne lifting gate. A six-lane highway runs along the crest, passing through a 1.2 km underwater tunnel beneath S-1.

Construction began in 1979, was about 70% complete when work halted in 1995 after the fall of the Soviet Union, and resumed in 2005 on President Vladimir Putin's orders. The complex was formally opened on 12 August 2011. Its first flood-protection use, on 28 November 2011, held back a 1.3 m surge and averted what would have been the city's 309th flood.

The structure is viewed by residents as a symbol of Russian engineering prowess and has become part of the city's daily landscape. Many people use the road built on top for commuting across the Gulf, making it a practical connection woven into everyday life.

The dam can be reached from several access points, and the road built on top offers wide views across the Gulf and the city. Visitors should remember that weather on the water can change quickly, so dressing appropriately is advisable.

The structure has special navigation openings that allow ships to pass through while maintaining the protective effect. This technical detail makes the construction more than a simple barrier, as it accounts for both ships and the city's needs.