About 50 kilometers long and 10-11 wide, that of Venice is the largest coastal lagoon in the upper Adriatic. Its history can be traced back to about 6000 years ago when, in the places now occupied by the lagoon, there was a part of the ancient Venetian plain, generated by the alluvial deposits of rivers such as the Brenta and the Piave. Along the coast, between the mouths of the rivers, the contribution of sands generated a long band of high dunes, which then formed a set of narrow islands parallel to the coast, the coastal strips; the latter, separating an internal body of water from the sea, gave life to the lagoon as we know it today. The lagoon settlements and the historic center of Venice have always been exposed to periodic flooding. The phenomenon of high water is linked to two components that influence the sea level: the rise of water due to the astronomical tide and the climate and the relative lowering of the soil compared to the average sea level. When the tide rises, in Venice the water begins to invade the lower areas of the city, including Piazza San Marco, the city center. In the days of “high water” some streets of the city are impassable and to walk you have to use raised walkways, arranged along predetermined paths. High waters compromise urban functionality and are a source of serious inconvenience for the population and economic activities; they are also responsible for the deterioration of the artistic and architectural heritage. The most dramatic flood that the Venetians remember occurred on November 4, 1966: that day the sea, driven by a strong sirocco wind, broke through the coast in two places and poured into the lagoon. Venice was completely submerged by a meter of water, with incalculable damage. Then the awareness emerged that the very survival of the city was in danger, if we had not intervened to defend it. Today numerous projects are being studied aimed at safeguarding the Venice lagoon, one of which is MOSE, which stands for MOdulo Sperimentale Elettromeccanico, meaning Experimental Electromechanical Module. MOSE is a project that consists in the construction of mobile dams that would come into operation in cases of emergency to regulate the water in the lagoon, isolate the Venetian Lagoon from Adriatic Sea preventing floods. The construction of MOSE started in 2003 and it should be completed by the end of 2021, even though it’s been successfully used in 2020.