I've included this postcard so you can see the phenomenon in action!

"Acqua alta" (or high water, as it is called) seems to have a special fondness for San Marco Square and the Basilica, where it can get more than 1 1/2 feet deep, so that, as you can see in the picture, it is possible to see a gondola navigating on the square or even beneath the arches.

Wooden platforms are set up for pedestrian traffic, so it can remain business as usual.