Practical Venice
Acqua alta in Venice: what to know
A natural lagoon phenomenon to understand without alarm: what it means, how long it lasts and how MOSE helps protect Venice.
Acqua alta is a natural, temporary phenomenon deeply connected with life in the lagoon. It does not mean that all of Venice is underwater: the city sits at different elevations, and lower areas such as St Mark’s Square are affected first.
What acqua alta really is
Temporary high tides depend on a combination of sea level, wind, atmospheric pressure and conditions in the Adriatic. Events are normally limited in time, and the same tide level can have very different effects in different parts of the city.
Why St Mark’s Square gets wet first
St Mark’s Square is one of the lowest areas of Venice and can begin to show the effects of the tide at lower levels than other parts of the city. Photos of water in the square therefore do not automatically mean that the whole city is flooded.
The MOSE system
Since 2020 Venice has had MOSE, the system of mobile barriers installed at the lagoon’s three inlets. When particularly high tides are forecast, the gates are raised to temporarily separate the lagoon from the Adriatic Sea. The system is operated according to forecasts and operational criteria, with the aim of protecting Venice from the most significant tides and keeping lagoon levels around the 110-centimetre threshold.
What to do during your visit
A forecast of acqua alta does not necessarily mean giving up your day in Venice. Check the level and peak time with the Tide Forecasting Centre, remember that some vaporetto routes may be altered, and follow local guidance. When necessary, wear suitable footwear and choose routes compatible with the forecast level.
The sirens are nothing to fear
When a significant tide is forecast, Venice uses an audible warning system. The signals communicate expected levels in advance and are part of the city’s normal management of high water.
Marghera Venice Apartments tip
Before changing your plans, always check the forecast level, the time of the peak and the areas affected: acqua alta is usually far more localised and temporary than photographs can make it seem.
Official information
Dates, programmes, fares and conditions may change. For variable information, always check the official source before your visit.
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