Water levels rose more than five feet (156cm / 61.4 inches), with photos showing locals and tourists wading their way through it.
The peak level of the water on Monday was the highest reached since December 2008, according to city statistics cited by AP.
The water levels even exceeded raised walkways in the city which are made for flooded areas, prompting their removal. Most of the city’s famous water bus system was also closed down.
Speaking on Monday, Venice Mayor Luigi Brugnaro said a series of underwater barriers would have prevented the rising water levels.
That project, dubbed ‘Moses,’ has been long delayed, with cost overruns and corruption scandals to blame.
Brugnaro said he had spoken with Premier Guiseppe Conte to stress the urgency of the Moses project, which would raise barriers when the tide reaches 109 centimeters (43 inches). That happens four times a year in Venice on average.
Much of Italy is under flooding alerts following heavy rains on Sunday and Monday, with high winds and toppled trees leading to at least five deaths.