Acqua alta, or the “High Water,” can make Venice feel like Atlantis. The phenomenon is often mistaken for proof that Venice is sinking.
At its worst, in 1966, acqua alta flooded the city with more than a meter of salty lagoon water; more typically, visitors notice water splashing over canal banks or bubbling up through drains in the Piazza San Marco.
Although the city did sink about 10 cm in the 20th Century because of industrial groundwater extraction, the sinking largely stopped when artesian wells on the mainland were capped in the 1960s.
The advice, is not to be conditioned by this phenomenon of high tide with which the Venetians have lived for years without particular problems and to take advantage to visit those places that the high tide can make more attractive.