The crisis has prompted the government to release €20 million in funds to tackle the devastation
Venice was on red alert for more floods and fierce winds on Saturday after an exceptionally high tide swamped the city of canals, where authorities have declared a state of emergency.
Mayor Luigi Brugnaro ordered the iconic St Mark's Square closed on Friday as the latest sea surge struck with strong storms and winds battering the region.
It reached a high of 5ft just before midday - lower than Tuesday's peak but still dangerous.
"I'm forced to close the square to avoid health risks for citizens a disaster," Brugnaro said.
In the afternoon the square reopened as water levels receded.
But civil protection authorities issued a weather "red alert" for the Venice region on Saturday, warning of violent winds.
Churches, shops and homes in the Unesco city have been inundated by unusually intense "acqua alta," or high water, which on Tuesday hit their highest level in half a century.
"We've destroyed Venice, we're talking about €1 billion in damage and that's just from the other day, not today," Brugnaro said.
The crisis has prompted the government to release €20 million in funds to tackle the devastation.
"It's shocking to see this, having water up to your knees," Mexican tourist Oscar Calzada, 19, told AFP Friday.
Surveying the damage, Culture Minister Dario Franceschini warned the task of repairing the city would be huge. More than 50 churches had suffered damage, he said.
"Seeing these places first-hand gives the sense of a much greater disaster than TV images show," Franceschini said.
Hotel reservations cancelled
Prime Minister Giuseppe Conte declared a state of emergency for the city on Thursday.
Residents whose houses have been hit are eligible for up to 5,000 euros in immediate government aid, while restaurant and shop owners can receive up to 20,000 euros and apply for more later.
Mayor Brugnaro on Friday also announced the opening of a fund where people in Italy and around the world could contribute to the historic city's repair.
One tourist, Italian Nicole Righetti, said she would be willing to pitch in.