A couple of weeks ago, we had a real aqua alta here. I am a bit late in sharing it with you because of technical difficulties (i.e the pics were on my brothers camera and he is in Germany!).
So, as you can hopefully tell from the pics, the water was several feet higher than normal around the edges and that translated to several inches worth in St. Marks and other squares. The entrance to the actual Basilica was filled with about 2-3 inches of water so everyone entered only through one door and via the walkways put up.
It was a great time to test out my new water boots and make sure there weren't any holes! The water came up past my ankles and my boots were secure (although not really good for warmth). It was definitely a cold day with a wind that I swore was straight from Siberia, but it was fun playing in the water like a kid again. Although I dont wish a flood on Venice of the kind like 1966 or so, I do hope to experience this phenomenon again!