Duny, Sandy beaches in Kurortny District, Saint Petersburg, Russia

Duny is a sandy beach on the Gulf of Finland in the Kurortny District of Saint Petersburg, about 30 km from the city centre, at the mouth of the northern branch of the Malaya Sestra River. Its dune landscape began forming over 5,000 years ago as the Littorina Sea retreated. Sparse Scots pine stands grow along the shore, and the sand is notably clean. Since 2024 the beach has had a boardwalk to the car park, changing rooms, toilets, volleyball posts, two children's playgrounds, lifeguard towers, benches, sun loungers and cycle parking.

The area around the Rayayoki river was a summer cottage spot for Petersburgers from the 18th century. The Finland Railway's Ollila halt opened in 1906, and the Primorsko-Sestroretsk road gained Kurort and Duny stations around 1900. After the 1940 Moscow Peace Treaty the coast passed to the USSR; in 1948 the Finnish toponym was renamed Duny, and a rest home of that name followed in 1979.

The beach's name, meaning "dunes," was given in 1948 when Finnish toponyms were renamed; the holiday house built in 1979 took the same name. From the early 1960s it became a known nudist beach, officially recognised in 1992. In 2024 wooden "DUNY" letters and seal figurines were installed at the entrance.

The beaches are easily reached by bus with regular service from central Saint Petersburg, making day trips convenient. The best visiting season is from June through September when weather is warm and most facilities are fully operational.

Two granite border posts with carved crosses and a later "USSR" inscription were dug up and set in the beach zone in 1986. During work on the Malaya Sestra riverbed, workers who did not know their value wanted to bury them; deputy A. A. Vaimer intervened and saved them. In 2014 posts 1 and 2 were moved to the Sestroretsky Rubezh museum.