Floating cities: reality or a utopia of the future?

The idea of living on water is not new – houseboats and stilt villages have existed around the world for centuries. What is new is the scale: architects and engineers are now designing entire floating neighbourhoods, linked by bridges, with a shared energy system and their own water management.

Behind these projects lie two serious problems of the modern world – rising sea levels and the shortage of land in large coastal cities. Let us look at which parts of floating architecture are already a reality and which are still a vision.

What is a floating city?

A floating city is a group of buildings, streets and public spaces built on floating platforms that are anchored but rise and fall with the water level. The buildings may be residential, office, public or mixed-use.

It is important to distinguish three things that are often confused:

• A floating building – a stand-alone building on a pontoon, such as an office or pavilion.
• A floating neighbourhood – a group of homes on water, linked by bridges and shared infrastructure.
• A floating city – a large, largely self-sufficient community with homes, work, food, energy and services. For now these exist mainly as concepts.

How does a building float?

A building floats because it sits on a platform that displaces enough water to carry its weight – the same principle by which a ship floats. Most often the platform is a hollow concrete hull or a structure with buoyant elements.

• Mooring: platforms are attached to vertical piles or held by cables and anchors so that they can move up and down but not drift away.
• Flexible connections: water, drainage and electricity are connected with flexible pipes and cables that allow for movement.
• Durability: materials must withstand constant moisture and, in seawater, salt as well.
• Stability: the centre of gravity is kept low so the building does not rock in waves and wind.

Which floating projects already exist?

The Netherlands – a country where much of the land lies below sea level – has the largest number of completed floating buildings and neighbourhoods.

Completed buildings and neighbourhoods

• Schoonschip, Amsterdam – a floating residential neighbourhood in which households share a common energy grid and are connected by a pedestrian jetty.
• IJburg, Amsterdam – this new district has an entire street of floating houses.
• Floating Pavilion, Rotterdam – a floating pavilion of transparent domes used for events and exhibitions.
• Floating Office Rotterdam – a timber office building on the water, designed by Powerhouse Company.
• Makoko Floating School, Lagos – a floating school by the architect Kunlé Adeyemi, which drew global attention to life in coastal communities.

What these projects have in common is that they sit in sheltered waters – canals, harbours and lakes, where waves are small and the link to the city is easy. It is there that floating architecture has proved it can work in everyday life, not just at exhibitions.

Concepts for true floating cities

Large floating cities are still at the concept and pilot stage, but some of them have prompted serious professional debate.

• Oceanix City – a concept of linked hexagonal platforms, developed with the involvement of Bjarke Ingels Group and in partnership with UN-Habitat, the United Nations programme for human settlements.
• Lilypad by Vincent Callebaut – a visionary design for a self-sustaining floating city in the shape of a water lily.
• The Seasteading Institute – an organisation that has for years been developing the idea of autonomous communities on the open sea.
• Blue21 – a Dutch company specialising in floating urban solutions.

What are the pros and cons of floating cities?

Floating buildings adapt to water instead of fighting it, but they are technically complex and carry their own risks. Here is the balance:

Pros

• Natural adaptation to flooding and rising water levels.
• New land for building in densely populated coastal cities.
• The possibility of moving or reconfiguring buildings.
• A direct connection with the water and a unique quality of life.

Cons

• Higher design and construction costs.
• Vulnerability in strong storms and waves, especially on the open sea.
• Complex infrastructure for water, drainage and energy.
• Possible impact on aquatic ecosystems – light, shade and pollution.
• Unclear or missing rules for building on water in many countries.

How is a floating project delivered, step by step?

A floating project begins with a detailed study of the water and ends with a long-term maintenance plan.

1. Site investigation. Depth, level fluctuations, currents, waves, ice and water quality.
2. Legal framework. Establishing whether and how building on water is possible at the specific location.
3. Concept and infrastructure. How the buildings will connect to one another and to the shore.
4. Design of the platform and building. Weight, stability and moisture-resistant materials.
5. Environmental assessment. Impact on flora, fauna and the shoreline.
6. Pilot phase. Building one or a few modules before expanding.
7. Maintenance. Regular inspection of the hull, moorings and flexible connections.

Are floating buildings possible in Bulgaria?

Technically, floating buildings are possible on calm bodies of water such as reservoirs, lakes, harbours and sheltered bays, but any such project requires careful clarification of the legal framework and of ownership of the water. More realistic for the Bulgarian context are floating pavilions, restaurants and platforms for leisure or sport, rather than whole neighbourhoods. The Danube and the Black Sea impose additional requirements because of currents, ice and waves.

A good starting point is to ask what the project is for. A floating sauna, a stage for summer events, a water sports base or a small pavilion on a reservoir are scales at which the technology is proven and the risks are manageable. A pilot project of this kind gives experience to the investor, the designers and the authorities before anything larger is contemplated.

Our approach at DARCH Projects

Unconventional ideas – on water, in the mountains or on difficult terrain – first need a clear concept that can be discussed with investors and authorities. That is exactly where DARCH Projects helps: designing the concept and presenting it through architectural animation and virtual reality, so that the project can be seen before it is built.

Frequently asked questions

Do floating cities already exist?

True floating cities with thousands of residents do not yet exist – they remain concepts and pilot projects such as Oceanix. There are, however, real floating neighbourhoods and buildings, mostly in the Netherlands: the Schoonschip residential neighbourhood and the floating houses of IJburg in Amsterdam, as well as floating pavilions and offices in Rotterdam.

How does a house float without sinking?

A floating house sits on a platform, most often a hollow concrete hull or a structure with buoyant elements, which displaces enough water to carry the building’s weight. The platform is moored to piles or held by anchors so that it moves up and down with the water level. Services are connected with flexible pipes and cables.

Is it safe to live in a floating house?

On calm, sheltered water such as canals, lakes and harbours, a well-designed floating house is safe and even more resilient to flooding than a conventional one, because it rises with the water. On the open sea the risks from storms and waves are much greater. Safety depends on site investigation, mooring, stability and regular maintenance.

Can a floating building be built in Bulgaria?

It is technically possible on calm water such as reservoirs, lakes and harbours, but every project requires careful clarification of the legal framework, ownership and permits for the specific location. More realistic first steps are floating pavilions, leisure or sports platforms and restaurants. A good start is a concept prepared by an architect for discussion with the relevant authorities.