In the northernmost section of the Adriatic Sea, where river Timavo flows, a coastal stretch characterized by low seabed and a complex lagoon structure begins. Including Venice, it ends with the delta of the Po river. Near the mouth of Timavo, there is the mouth of Isonzo, which springs from Alpi Giulie in Slovenia and ends its course in the gulf of Trieste, between Monfalcone and Grado. The Nature Reserve of the mouth of Isonzo covers a surface area of about 2,400 ha situated along the last 15 km of the course of the river. The territory of the Nature Reserve involves the Municipalities of Staranzano, San Canzian d'Isonzo, Grado, and Fiumicello.