The MOSE Flood Barriers Site Features

The system spans the lagoon's three inlets -- Lido (with two barriers either side of an artificial island), Malamocco and Chioggia -- with 78 gates in total.

Each gate is a hollow steel box roughly twenty metres wide, hinged along its bottom edge to a concrete caisson sunk into the seabed. At rest it lies flat in its housing, flooded and level with the floor of the channel.

To raise it, compressed air is pumped in and the water forced out; the gate becomes buoyant and swings up to sit at an angle above the surface. To lower it, the air is released and it sinks back.

The visible works are the service infrastructure rather than the gates themselves: locks at Malamocco for shipping, breakwaters, an artificial island at the Lido inlet, and control buildings.

The design was chosen specifically so that nothing stands permanently across the inlets -- when MOSE is not in use, the lagoon looks as it always has.

The three inlets

Lido, Malamocco and Chioggia -- the only openings between the Adriatic and the lagoon, and therefore the only places a barrier could go. The Lido inlet is split into two barriers either side of an artificial island.

The gates

Seventy-eight steel boxes, each around twenty metres wide, hinged to concrete caissons on the seabed. Their whole design principle is invisibility at rest.

The Malamocco lock

A navigation lock lets shipping reach the industrial port at Marghera while the barriers are raised -- the one part of the system that has to work continuously.

Punta Sabbioni

The most accessible vantage point on the works, and a normal stop on the Venice boat.

The lagoon exchanges water with the Adriatic through only three inlets, and everything about MOSE follows from that: close those three gaps and the lagoon is sealed.

Each inlet is a deep channel between barrier islands -- Lido between the Cavallino peninsula and the Lido di Venezia, Malamocco between the Lido and Pellestrina, and Chioggia between Pellestrina and Sottomarina.

These are the same openings the Republic spent centuries managing with breakwaters and the murazzi, for the same reason.

The works have physically altered the inlets: breakwaters have been extended, an artificial island built at the Lido, and the channel floors dredged and rebuilt to take the caissons.