All Venetians pride themselves on having a good pair of Wellington boots at home. The fact is the words acqua alta have many meanings for the inhabitants of the lagoon, since, given the unique geographical location of the city, floods caused by the high tide are frequent.

A complex series of natural phenomena combine to cause this situation, but the problem is largely due to the particular tendency to experience important effects of the tides of the Adriatic Sea, a veritable cul de sac closed off between the Italian Peninsula and the Balkan Peninsula.

By definition, one usually talks of acqua alta when the water enters the three main ways of the lagoon and reaches at least 9 centimetres above the zero tide level. The Piazza San Marco, one of the lowest points of the city, is often one of the first public spaces affected, and it is now a classic sight, especially in winter, to see the  locals and tourists alike moving cautiously along the wooden walkways placed for this purpose. Sometimes the pavement of the square is more than 30 centimetres below the water level.

The phenomenon is particularly worrying when you realise that Venice is, by nature, a humid city, which means that the foundations of many of its buildings, including authentic jewels such as the Renaissance palaces or churches, are slowly sinking. In fact, it is easy to see how the floors of the ground floor of many of these buildings have taken on, after many acque alte, an undulating outline.

Today they are working on a sophisticated system, the MOSE Project, which consists of a series of 7 moving floodgates situated strategically in the three entrances to the lagoon, and which will be automatically closed when the forecast is for a particularly high tide. 

Although there is consensus between the scientific community and the politicians about the usefulness of this initiative, the project has caused great consternation among some sectors of the population, above all among the ecology groups, who consider the MOSE Project is a serious threat to the marine fauna of the lagoon. The construction of this complex system of dykes to control the flow of the tides began in 2003, and it is planned to have the works completed in 2010.