Is Venice Really Sinking? The Truth About Flooding in the City of Canals

Venice has captivated visitors for centuries with its otherworldly beauty—grand palazzos rising directly from the water, gondolas gliding through narrow canals, and bridges connecting a labyrinth of islands. Yet behind this romantic façade lies a sobering reality: Venice is facing an existential crisis. The question isn’t whether Venice floods, but rather how much longer this UNESCO World Heritage city can survive against rising waters and sinking foundations.

The Reality of Acqua Alta

“Acqua alta,” meaning “high water” in Italian, is the term Venetians use for the periodic flooding that has plagued their city for generations. This phenomenon occurs when a combination of factors—high tides, strong sirocco winds from the south, and low atmospheric pressure—push water from the Adriatic Sea into the Venetian Lagoon, causing the city’s canals to overflow into streets and squares.

Contrary to popular belief, acqua alta is not a new problem. Historical records document flooding events dating back centuries. However, what has changed dramatically is the frequency and severity of these floods. In the early 20th century, St. Mark’s Square flooded approximately seven times per year. By the 1990s, this had increased to roughly 60 times annually. Today, some level of flooding occurs over 100 times per year in low-lying areas.

The most catastrophic recent event occurred on November 12, 2019, when water levels reached 187 centimeters above normal sea level—the second-highest flood in recorded history, surpassed only by the devastating 194-centimeter flood of 1966. The 2019 flood caused an estimated €1 billion in damage, destroying businesses, homes, and priceless historical artifacts while highlighting Venice’s vulnerability to climate change.

Why Is Venice Sinking?

Understanding Venice’s flooding crisis requires examining two separate but interconnected problems: the city is both sinking and the sea level is rising. This double threat creates a perfect storm for the floating city.

Venice was built on 118 small islands in a shallow lagoon, supported by millions of wooden pilings driven deep into the marshy ground. For centuries, this foundation proved remarkably stable. However, during the 20th century, excessive groundwater extraction for industrial use on the nearby mainland caused the city to sink by approximately 12 centimeters between 1950 and 1970. Though this practice ceased in the 1970s, the damage was done.

Natural geological subsidence—the gradual compacting of sediment beneath the lagoon—continues at a rate of 1-2 millimeters per year. This might seem negligible, but combined with rising sea levels, the cumulative effect is profound. The Adriatic Sea has risen by approximately 2.5 millimeters per year over the past century, with predictions suggesting this rate will accelerate dramatically in coming decades.

Climate change amplifies these threats. As global temperatures rise, thermal expansion of seawater and melting polar ice contribute to rising ocean levels. Scientific projections estimate that sea levels around Venice could rise by 82-100 centimeters by the end of this century under pessimistic scenarios, which would render much of the city uninhabitable without significant intervention.

The MOSE Project: Venice’s €7 Billion Gamble

In response to the existential threat facing Venice, Italian authorities embarked on one of the world’s most ambitious engineering projects: MOSE (Modulo Sperimentale Elettromeccanico), a system of 78 mobile barriers designed to temporarily separate the Venetian Lagoon from the Adriatic Sea during high tides.

The project, which began construction in 2003, consists of rows of yellow hollow gates that normally lie flat on the seabed at three inlets connecting the lagoon to the sea. When forecasters predict acqua alta exceeding 110 centimeters, compressed air is pumped into the barriers, causing them to rise and form a temporary dam that prevents tidal waters from entering the lagoon.

After decades of delays, cost overruns, and corruption scandals that imprisoned dozens of officials and contractors, MOSE became operational in 2020. During its first activations, the system successfully prevented flooding in Venice, offering hope that the city might be saved. Since then, MOSE has been activated dozens of times, generally proving effective at protecting the city from high water.

However, MOSE is not a permanent solution. The barriers were designed to handle sea levels of up to 60 centimeters above current levels and can only be deployed for limited periods—prolonged closure cuts off the lagoon’s connection to the sea, threatening the ecosystem and preventing maritime traffic. As sea levels continue to rise, MOSE will require increasingly frequent activation, potentially dozens of times per month, which would severely disrupt Venice’s economy and maritime connections.

Furthermore, the system requires continuous maintenance and has already shown signs of wear. Some experts question whether MOSE can function effectively beyond 2050, when sea level rise may exceed the system’s design parameters.

Life During Acqua Alta

Despite the flooding threat, Venice remains inhabited by approximately 50,000 residents—down from over 170,000 in the 1950s. Venetians have adapted to living with periodic flooding through a combination of practical measures and stoic acceptance.

When sirens sound throughout the city warning of impending acqua alta, residents spring into action. Shopkeepers place waterproof barriers across doorways and move merchandise to higher shelves. Residents don rubber boots and plan routes using elevated wooden walkways called “passerelle” that authorities erect along major thoroughfares.

St. Mark’s Square, being one of the lowest points in Venice at approximately 90 centimeters above normal sea level, floods regularly even during minor acqua alta events. Tourists and locals wade through ankle-deep water or navigate the temporary walkways, creating surreal scenes of everyday life continuing amid the flood.

For visitors, experiencing mild acqua alta can actually be memorable rather than disruptive. The city takes on an even more otherworldly quality when water laps at building foundations and reflects the lights of palazzos in flooded squares. However, severe flooding of 140 centimeters or higher creates dangerous conditions, damages infrastructure, and can trap people in buildings.

Traditional activities like gondola rides in Venice continue even during moderate flooding, as the city’s waterways are, after all, designed for navigation. The iconic gondoliers skillfully navigate the elevated water levels, though some low bridges may become impassable when water rises too high.

The Environmental Impact

The flooding crisis affects more than just Venice’s buildings and residents—it threatens the delicate ecosystem of the Venetian Lagoon, a unique environment supporting diverse marine life and providing critical habitat for migratory birds.

Frequent activation of the MOSE barriers disrupts the natural tidal exchange between the lagoon and the Adriatic Sea. This reduced water circulation can lead to decreased oxygen levels, increased water temperature, and accumulation of pollutants in the lagoon. The ecological consequences could be severe, potentially transforming the lagoon’s ecosystem in ways that are difficult to predict.

Additionally, the lagoon’s natural morphology has been dramatically altered over centuries through human intervention. Navigation channels dredged for large ships have deepened the lagoon, accelerating the flow of high tides toward Venice. The loss of salt marshes and mudflats that historically absorbed tidal energy has further increased the city’s vulnerability to flooding.

Tourism’s Double-Edged Sword

Tourism brings approximately 25-30 million visitors to Venice annually, making it one of the world’s most visited cities relative to its population. While this generates crucial economic revenue, overtourism contributes to Venice’s challenges in multiple ways.

Large cruise ships that once sailed directly past St. Mark’s Square created waves that eroded building foundations and stirred up sediment. After years of protests, authorities banned large cruise ships from the historic center in 2021, though they still dock at the industrial port area, and their overall impact on the lagoon remains controversial.

The weight of millions of tourists walking Venice’s streets and bridges, combined with the vibrations from water traffic, may contribute to structural deterioration, though the exact impact is difficult to quantify. More significantly, tourism-driven property prices have accelerated the exodus of Venetian residents, transforming the city into what critics call “Disneyland on water”—a theme park increasingly detached from authentic local life.

Can Venice Be Saved?

The question of Venice’s long-term survival elicits varied responses from experts. Optimists point to MOSE’s success and argue that with continued investment in flood defenses, building restoration, and population retention programs, Venice can survive and thrive for generations to come.

Pessimists counter that MOSE merely buys time and that without dramatic global action on climate change, Venice faces inevitable abandonment within this century. They note that even with the barriers, Venice will require constant, expensive maintenance and adaptation as sea levels continue rising.

A middle view suggests Venice’s future depends on a multifaceted approach: maintaining and upgrading MOSE, raising ground floors of buildings, restricting tourism to sustainable levels, incentivizing residents to stay, and pursuing global climate action. Some radical proposals include raising the entire city through hydraulic jacking—a technique successfully used to save historic structures—though the cost and complexity would be staggering.

Several buildings and neighborhoods have implemented local solutions. Waterproof barriers, elevated doorways, and flood-resistant building materials help individual structures withstand regular inundation. Some ground-floor spaces have been permanently abandoned, effectively treating acqua alta as the new normal baseline.

What This Means for Visitors

Should you visit Venice? Absolutely—but perhaps with more urgency than before. The city’s unique beauty and cultural significance make it irreplaceable, and experiencing Venice firsthand creates memories that photographs cannot capture.

Plan your visit during late spring or early autumn to avoid both summer crowds and the winter acqua alta season, which peaks from October through January. If you do visit during flood season, consider it part of the authentic Venetian experience rather than an inconvenience. Pack rubber boots or waterproof shoes, and check flood forecasts through the city’s official app or website.

Support local businesses, stay in locally-owned accommodations, and contribute to Venice’s economy in ways that benefit residents rather than just extracting from the city. Respect the fragile environment by following local guidelines and treating this living museum city with the care it deserves.

The Broader Warning

Venice serves as a canary in the coal mine for coastal cities worldwide. From Miami to Bangkok, from Shanghai to Amsterdam, hundreds of millions of people live in low-lying coastal areas threatened by rising seas. Venice’s struggle highlights the reality that climate change isn’t a distant future threat—it’s reshaping our world today.

The solutions Venice implements or fails to implement will inform strategies for coastal cities globally. MOSE demonstrates that engineering can provide temporary protection, but also reveals the staggering costs and limitations of technological fixes without addressing root causes.

The Truth About Venice Flooding

So, is Venice really flooding? Yes, unequivocally. The city faces more frequent and severe flooding than ever before, driven by subsidence, rising sea levels, and climate change. MOSE provides temporary protection but is not a permanent solution, and Venice’s long-term survival remains uncertain.

However, Venice is not doomed to sink beneath the waves next year or even next decade. The city has survived 1,600 years of challenges and continues adapting to new threats. With continued investment, international support, and global action on climate change, Venice may survive far into the future.

What is certain is that Venice is changing. The question isn’t whether we’ll lose Venice as it exists today—that process is already underway as residents leave and floods increase—but whether we can preserve enough of its essence for future generations to understand why this impossible city, built on water, captured humanity’s imagination for centuries.

Visit Venice while you can, support its survival, and let its beauty and fragility inspire action on the climate crisis that threatens coastal communities worldwide. Venice is flooding, but it’s not gone yet—and whether it survives depends on choices we make today.