Acqua alta and St Mark's Basilica

Acqua alta, the high tide that pushes water into the lower parts of Venice, can flood St Mark's Square, and the Basilica stands on it. The Basilica's access rules don't close the church when it happens: if water comes into the narthex, the entrance hall, the Procuratoria di San Marco sets out alternative routes, signposted and supervised by its own staff, and visitors must use the walkways. This page covers what that means on the day, how the building is now protected and what the MOSE barriers do.

What happens to the visit when the water comes in?

The regulation is short and practical. When high water enters the narthex, routes are decided case by case, marked with signs and watched by custodians. Your part is to follow them and stay on the raised walkways rather than wading around them.

A few things follow from that:

• Your ticket stays tied to its date and time slot, so arrive on time even if the square is wet. The official terms allow a margin of up to 15 minutes either side of your slot; the official FAQ speaks of about 5 minutes.
• Walkways are narrow and slow. Allow extra time to cross the square and reach the entrance.
• Opening times can change, so if a high tide is forecast, check the Basilica's official site before setting out.
• Wear waterproof boots or carry overshoes. Bags still have to be no larger than 40×30×20 cm and there is a metal detector at the door; see the dress code and rules.

Has the Basilica been damaged by flooding?

Yes. In a press release of April 2025 the Procuratoria described the 2019 acqua granda as the most serious event, when seawater entered through the windows of the crypt, the low chamber where the body of St Mark was laid in 1094.

How is the Basilica protected now?

Two pieces of work protect the building:

• A glass barrier on St Mark's Square guards the front and the side of the Basilica.
• Works on the rear, on the Rio della Canonica side, were completed in April 2025. According to the Procuratoria they complete the protection of the whole Basilica together with the barrier on the square.

The same press release set out plans to move the info point and shop out of the narthex into the Ateneo San Basso, on the Piazzetta dei Leoncini, and to restore the narthex. The Procuratoria gave the end of 2026 as its target; whether that has happened has not been confirmed, so don't count on it when you plan.

What is MOSE and does it keep the square dry?

MOSE is a system of mobile barriers at the inlets that connect the Venetian lagoon to the sea: Lido, Malamocco and Chioggia. When a high tide is expected, the barriers are raised to hold the sea back from the lagoon. It is run by the Autorità per la Laguna di Venezia, which publishes a table of every closure.

The first closure with all the barriers raised was on 3 October 2020. Since then, the official table counts these closures per season:

The 2026/27 season had one closure by 10 November 2026, on 21 October 2026.

The official sources we use do not publish the tide level at which the barriers are raised, so we don't quote one. For a visitor, the point is that the Basilica keeps its own glass barrier and its walkway plan as well as relying on MOSE.

When is acqua alta most likely?

No official source we use publishes a calendar of high tides, and the closure figures above show how much one season can differ from the next. Check the tide forecast the evening before your visit and pack waterproof footwear if high water is expected.

Do I need to pay the Venice access fee?

The access fee (contributo di accesso) is a charge set by the City of Venice for entering the city on specific days, within set hours. It is separate from any Basilica ticket.

The 2026 trial is over, and from 27 July 2026 the fee no longer applies.

The fee will be due again in 2027, from 8.30am to 4.30pm, on these 72 days:

• March 2027: 26, 27, 28, 29
• April 2027: 2, 3, 4, 9, 10, 11, 16, 17, 18, 23, 24, 25, 26, 27, 28, 29, 30
• May 2027: 1, 2, 7, 8, 9, 14, 15, 16, 21, 22, 23, 28, 29, 30, 31
• June 2027: 1, 2, 3, 4, 5, 6, 11, 12, 13, 18, 19, 20, 25, 26, 27
• July 2027: 2, 3, 4, 9, 10, 11, 16, 17, 18, 23, 24, 25, 30, 31
• August 2027: 1, 6, 7, 8, 13, 14, 15

The City says the arrangements for 2027 will be announced by 31 December 2026.

The 2027 amounts and exemptions had not been published by 10 November 2026. Check the official access fee site before a day trip on one of those dates.

Planning a visit in the high-water season

• The Basilica opens at 9.30am (2pm on Sundays and holy days of obligation), with last entry at 4.45pm; full times are on our opening hours page.
• Get to the square with time to spare; walkways slow everyone down.
• Keep the visit compact: the route inside lasts at most 20 minutes, the Pala d'Oro 10.
• The Museum and Horses' Loggia are upstairs, above the narthex, on a separate ticket.

How to reach the square by water bus, and which stops to use, is on getting to St Mark's Basilica.