​PETROVSK, a seaport of Russia in Transcaucasia, on the Caspian Sea, in the province of Daghestan, 180 m by rail E. of Vladikavkaz, and 235 m. N.W. from Baku. Pop. 9806. The town has become the port of embarkation for Krasnovodsk, the Transcaspian territory, and the Central Asian khanates. There are naphtha wells, and the hot sulphur baths at Ak-gol and Talga, close by, attract many visitors in summer.