Walkways were removed from St Mark's Square, which is now closed
Flooded Venice has been hit by a new high tide of 160cm (5.3ft), giving residents no respite from a crisis costing millions of euros.
World-famous St Mark's Square, a magnet for tourists, has been closed, and schools are shut for a third day.
The 187cm peak on Tuesday was the highest level for more than 50 years, damaging cultural monuments, businesses and homes. More than 80% of the canal city was flooded.
The government declared a state of emergency in the Unesco world heritage site.
Residents with flood-damaged homes will get up to €5,000 (£4,300; $5,500), and businesses up to €20,000 in compensation.
The BBC's Jenny Hill in Venice writes:
Nearby streets quickly flooded. Tourists, shoes covered in plastic bags, carried their luggage along raised narrow trestle walkways, which the authorities have put up to keep the pedestrian traffic moving.
The Grand Canal's water is now level with the pavement
"It hurts to see the city so damaged, its artistic heritage compromised, its commercial activities on its knees," Prime Minister Giuseppe Conte, who visited Venice on Wednesday, wrote in a Facebook post (in Italian).
The city is made up of more than 100 islands inside a lagoon off the north-east coast of Italy. It suffers flooding on a yearly basis.
The government has pledged to release €20m in aid for Venice.
Only once since official records began in 1923 has the tide been higher than it reached this week - hitting 194cm in 1966.
The mayor of Venice, Luigi Brugnaro, blamed climate change for the flood, saying the impact was "huge" and would leave "a permanent mark". Strong winds lashing the area are contributing to the crisis.
Mr Conte said the government would accelerate the building of structural defences for the city, referring specifically to the so-called Mose project - a hydraulic barrier system to shut off the lagoon in the event of rising sea levels and winter storms.
Edited from the BBC