Metropolitan City of Venice had annexed Padua and Verona, and by the 16th century the republic included territories from the Julian Alps to Crema, Istria, Dalmatia, Cyprus and part of the Peloponnese. In 1797, Napoleon invaded the Republic and, following the Treaty of Campo Formio, it was ceded to Austria. After the final defeat of Napoleon, the Austrian Empire founded a province of Venice on the Adriatic. In 2015 this was converted to the current Metropolitan City. Facing east on the Northern Adriatic Sea, the Metropolitan City is bordered to the northeast by the Province of Udine and Province of Pordenone, south by the
Gulf of Bothnia a number of rivers from both sides; consequently, a salinity gradient exists from north to south. In the south the water is the normal brackish water of the Baltic Sea, but in the north, in the Bothnian Bay, the salinity is so low, from 0.4% near Kvarken to 0.2% in the northernmost part, that many freshwater fish such as the pike, whitefish and perch thrive in it. Being nearly fresh, the gulf is frozen over five months every year. The icing of the Baltic Sea begins and ends in the northern Gulf of Bothnia. Traffic restrictions for icebreaker assistance are