The Site stretches along the downstream 15 kilometres of the River Isonzo, including the river mouth at the far north of the Adriatic Sea and a considerable area of shallow sea. This wetland lies at the northernmost end of a system of about 100,000 hectares of coastal lagoons, which includes the mouth of the River Po and Venice lagoon, where it reaches the limestone uplands of the high calcareous coasts of the Western Balkans. This convergence contributes to the notable biodiversity value of the Site. Its geomorphological setting, as a junction between low and high shores, further adds to the Site’s value as a biogenetic reserve in an area which is significantly altered by human activity. Foce dell’Isonzo – Isola della Cona regularly hosts significant numbers of waterfowl and other rare animal and plant species, and is a reproduction site for fish such as the marbled trout Salmo marmoratus and birds including the greylag goose Anser anser. It is important for ecotourism, especially birdwatching, with over 50,000 visitors a year, and for environmental education and research. The main threat to the Site is canalization and river regulation.