History of the Republic of Venice a powerful fleet sailed from Venice, to resolve the problem of the Narentine pirates. The fleet visited all the main Istrian and Dalmatian cities, whose citizen, exhausted by the wars between the Croatian king Svetislav and his brother Cresimir, swore an oath of fidelity to Venice. the Main Narentine harbours (Lagosta, Lissa and Curzola) tried to resist, but they were conquered and destroyed (see: battle of Lastovo). The Narentine pirates were suppressed permanently and disappeared. Dalmatia formally remained under Byzantine rule, but Orseolo became "Dux Dalmatie" (Duke of Dalmatia"), establishing the prominence of Venice over the Adriatic Sea. The "Marriage
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