World-famous St Mark's Square, a magnet for tourists, has been closed, and schools are shut for a third day.
The canal city's famous waterbuses - the vaporetti - are not running.
The 6 feet peak on Tuesday was the highest level in more than 50 years, damaging monuments, shops and homes.
More than 80% of the city was flooded.
The government declared a state of emergency in the UNESCO world heritage site.