78 gates, 100 liftings: how MOSE holds Venice

The MOSE has been raised 100¹ times since it entered service in 2020, reaching that number on March 12, 2025, with 78 mobile gates across the three inlets of the Venice lagoon.

78 gates in four barriers at three inlets

The system is 78 mobile gates grouped into 4 barriers, one at each of the 3 openings between the lagoon and the Adriatic: Lido, Malamocco and Chioggia. Four barriers for three inlets, because one of the openings is closed by two of them.

The gates rest on the lagoon floor and come up only when a closure is ordered. That is why nothing of the system is visible from the city on an ordinary day, and why it vanishes again once the tide falls.

It is engineered for a tide of 3 meters. No tide close to that has been put to it so far, so the design figure is headroom rather than a forecast.

The hundredth lifting was on March 12, 2025

Lifting number 100¹ came on March 12, 2025, counting from the start of operational service in 2020. That covers the tide seasons from 2020 to 2025, not a test program.

The Ministry of Infrastructure and Transport puts the damage those 100¹ closures avoided at more than 2.6 billion euros. Treat it as what it is, a government estimate of losses that did not happen, and note who signed it.

The worst tide so far: November 22, 2022

The highest water the barriers have held back was above 1.80 meters, on November 22, 2022. The gates closed and the lagoon stayed where it was.

Set that against the 3 meter design ceiling and you have the honest measure of the system: it has been tested well inside its stated limit, and the top of the range remains theory.

Nobody publishes the trigger height, and it matters

The tide level at which the barriers are ordered up is not stated on any official page we could read, so this page does not print a number for it. That single figure decides how often the lagoon is closed and therefore how often ships wait.

Press accounts describe a threshold lowered in steps, from 130¹ to 120¹ to 110¹ centimeters. We did not find it on a primary source and we are not repeating it as fact.

If you are in Venice in November and want to know whether the barriers are up today, the operating notices are the thing to check, not a number written in a travel article eighteen months ago.

What a closure looks like from the city

A closure lasts as long as the tide stays above the level that triggered it, and 100¹ of them have been ordered since 2020. From a hotel window you see none of it.

While the 4 barriers are up, the 3 inlets are shut, and those inlets are also how ships reach the port. Every closure is therefore a decision with a cost attached to it, taken tide by tide, which is why the trigger level is an operational question and not a technical detail.

The visible part of the system is the water that does not arrive. Piazza San Marco is the lowest point of the city and the first place that floods; on a closure day it stays dry, and nothing on the pavement tells you why.

What this changes for a visit

Acqua alta in Venice is now a managed event rather than an inevitable one, and that is the practical content of those 100¹ liftings. Boots in the hotel lobby are no longer the standard autumn image of the city.

It does not follow that every high water is stopped. The barriers close on a decision, taken tide by tide, and the walkways still come out when the water gets into the lowest squares.

For the fee that most sites still tell you to pay at the station, see why the Venice access fee is not in force. For the city itself, start at Venice.

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