Gulf of Venice, Italian Golfo Di Venezia, northern section of the Adriatic Sea (an arm of the Mediterranean Sea), extending eastward for 60 miles (95 km) from the Po River delta, Italy, to the coast of Istria, in Slovenia and Croatia. It receives the Po, Adige, Piave, and Tagliamento rivers. Marshes, lagoons, and sandspits border the gulf’s shores as far as Trieste, Italy, where the low plateau of the Istrian Peninsula begins. A northeast wind, called the bora, causes rough seas and creates shipping hazards in the gulf.
The rise of the city of Venice as a maritime power at the northwestern end of the gulf gave special importance to Adriatic shipping routes in the Middle Ages. Modern ports along the gulf, apart from Venice, include Pula and Rovinj (both in Croatia) and Trieste, which is located on a northeastern inlet, the Gulf of Trieste.