Acqua Alta (High Water), Venice
High water in Venice looking towards the basilica of St. Mark. Not a single living soul around at 1am when this picture was taken. The square and adjacent streets were covered with about 20cm of water. For March in Venice this is not very much.
More on the Aqua Alta phenomenon:
"Acqua alta (high water) has become a fact of life in Venice. The lagoon water level occasionally rises above the level of the plazas and streets, flooding them. This will happen several times a year, usually in the colder months. Acqua alta usually lasts a couple of hours. You'll see raised walkways in side alleys ready to be pulled out when acqua alta hits. When the city begins to flood, sirens will sound to warn residents and businesses. If you speak fluent Italiano, tune into news programs since their predictions of the times the flood begins and ends are usually on the spot." - Wikitravel