For a few days a year, usually in autumn and winter, you may find high water in the streets (calli) and squares (campielli).
It is caused by a series of phenomena – the strong south-east wind, the Adriatic sea-currents, low pressure, etc. – the sea level rises to flood the lower areas of the city. These are floods of no more than a few centimeters that only last a couple of hours. The tide then goes out and everything returns to normal.
As a rule, you only need to wear a pair of rubber boots; but nevertheless access to the whole city is guaranteed. You can still reach the main places of the city on foot thanks to raised pedestrian platforms that allow you to cross the points where water would otherwise prevent you from doing so.
But how high does the high water get?
When an exceptional tide is forecast, that is over 140 centimeters, which rarely occurs, about 60% of the historical centre is flooded, with a level that goes from a few centimeters to about 60 centimeters in St.Mark’s Square, the lowest area of the city.