Breakwaters: Climate Change Solutions Reshaping Global Maritime Traffic

At the first light of dawn, in the stretch of sea overlooking the port of Genoa, the thirteenth caisson slowly glides down towards the seabed, 50 metres deep.

Sixty-seven metres long, thirty wide, thirty-three high: a cathedral of reinforced concrete that disappears into the blue in an operation lasting nearly an entire day. Six pumps work in synchrony to fill the caisson’s internal chambers with water, guiding its descent to the seabed.

It is the largest caisson ever built in Italy, created for the Genoa New Breakwater: a structure more than six kilometres long, made up of over 100 elements sunk side by side. Behind the spectacle of the sinking lies the precision of an industrial process: the caissons are constructed atop a semi-submersible barge, completed while floating, and then launched.

The result is the creation, piece by piece, of an invisible yet vital barrier that will protect the port of Genoa from storm surges, enable the entry of the world’s largest ships, and pave the way for more sustainable maritime logistics.

The story of the Genoa port, where the PerGenova Breakwater Consortium led by Webuild is constructing what will become Europe’s deepest breakwater, is that of a strategic infrastructure which, all over the world, has become a central element in maritime trade logistics.

Breakwaters are designed to shield ports from waves and winds, stabilise seabeds, and create new port spaces. Today, the most advanced are built using reinforced concrete cellular caissons (like Genoa’s breakwater), enormous prefabricated modules sunk and aligned with millimetric precision. Each caisson can weigh up to 30,000 tonnes and contain thousands of cubic metres of water, forming a dynamic equilibrium between buoyancy and gravity.

Where once breakwaters were made of natural rock mounds, today they are complex engineering organisms designed to withstand ten-metre waves, earthquakes, rising sea levels, and pressure changes caused by climate change. They are solutions adopted by cities that have chosen sea freight as a lever of both regional and national development.

No port has transformed the relationship between city and sea quite like Rotterdam. Here, at the mouth of the Rhine and Meuse rivers, stands the Maeslantkering, one of the most imposing movable barriers on the planet: two steel arms, each 210 metres long, that close like a gigantic mechanical lock during storms to protect the port and all of southern Holland.

Upstream, the Europoort breakwater forms a system of modular caissons and wave breakers that safeguard Europe’s largest logistics platform. The result is a combination of engineering and resilience so successful that Rotterdam is now considered a global laboratory for sea-adaptive infrastructures and maritime technology, where every breakwater is part of an urban ecosystem.

Thousands of kilometres away, in Tokyo Bay, rises one of the deepest and most complex breakwaters in the world.

Built to protect the port and city from tsunamis and typhoons, it stretches over 11 kilometres, with caissons more than 40 metres high and seismic-resistant bases capable of withstanding magnitude-8 waves. Each element was prefabricated on land and towed to its installation site, where divers and underwater drones checked the alignment to within a centimetre.

The Tokyo breakwater is a monument to Japanese precision, a work demonstrating how marine engineering has become an integral part of civil and urban defence.

In Hong Kong, the breakwater of the artificial island of Chek Lap Kok, home to the international airport, represents one of the boldest feats of contemporary maritime engineering. The 13-kilometre-long barrier was built using prefabricated caissons and artificial reefs that made it possible to “recreate” an entire island in the heart of the Pearl River Delta.

The same logic applies to Singapore, where the scarcity of space has pushed the nation to construct multifunctional breakwaters: structures that simultaneously defend against the sea, generate energy, and host roads or suspended gardens. The 350-metre-long Marina Barrage regulates water levels, prevents flooding, and provides the city with a significant freshwater reserve.

Rising sea levels and the increasing intensity of coastal storms are bringing breakwaters back to the forefront of urban planning.

According to the World Bank, by 2050 over 800 million people will live in coastal areas at risk of flooding. Ports, which handle 90% of global trade, are the most exposed infrastructures in this context.

This is why the term “marine megastructures” is increasingly being used to describe works that integrate defence, logistics, and energy functions. Breakwaters that double as piers, platforms for wind turbines, solutions to climate change, and even artificial habitats for marine fauna.

The challenge, therefore, is to build them while reducing environmental impact, using low-emission concretes, recycled steel, and digital construction processes, exactly as is being done for Genoa’s new breakwater.

In this global scenario, the Genoa New Breakwater stands as a prime example of innovation applied to the sea. Built by the PerGenova Breakwater Consortium led by Webuild, the project serves as a laboratory of breakwater construction techniques combining marine engineering, sustainability, and digitalisation.

The caissons are manufactured entirely within the port of Genoa, reducing maritime transport and emissions, and sunk using a remote-controlled system equipped with GPS sensors and digital twin models to verify every stage.

The new breakwater will allow access for container ships up to 400 metres long and will provide the port with protection against increasingly intense and frequent storm surges caused by climate change. A breakwater that – by its very nature – not only defends Genoa, but also redefines Italy’s role within the Mediterranean marine transport logistics.