Building underwater – the challenges and opportunities

Even though we have already seen examples of underwater hotels and research facilities, building beneath the sea represents one of the most ambitious and innovative frontiers in modern construction and engineering, However, there is now real talk of constructing submerged cities and this means that the concept of building beneath the waves is becoming increasingly viable due to advancements in technology and material science. Yet, while the potential benefits are substantial, the challenges are equally daunting, writes John Ridgeway.

Constructing underwater is fraught with technical, environmental and logistical challenges and needs innovative solutions and meticulous planning to ensure successful project execution. Water pressure, for example, increases with depth, creating a hostile environment for construction. At just 10 metres below the surface, the pressure doubles compared to atmospheric levels. This poses a significant challenge for structural integrity and worker safety.

Engineers must therefore design buildings to withstand immense forces while also considering buoyancy, which creates an upward force on submerged structures, potentially destabilising them. To counteract these forces, advanced materials such as reinforced concrete, steel alloys and high-performance composites need to be used to create pressure-resistant and durable structures. Anchoring systems to ensure stability will also be a key part of any underwater building.

Furthermore, keeping structures watertight is obviously crucial for underwater buildings. Even minor leaks can compromise structural integrity, lead to corrosion, or damage internal systems and equipment. Waterproof membranes, specialised sealants and double-shell construction will need to be employed to prevent water ingress. Regular maintenance and inspections will be equally essential to address wear and tear.

Construction logistics

We already know that building underwater requires specialised equipment and methodologies. Traditional construction techniques are often unfeasible, necessitating innovations such as prefabrication, where components are assembled on land and then transported underwater.

Cofferdams, temporary enclosures, used to create dry working environments, would also be needed. Furthermore, skilled divers and remotely operated vehicles (ROVs) would be integral to underwater construction.

We also need to be aware that underwater construction can significantly disrupt marine ecosystems. Activities such as dredging, material dumping and noise pollution can harm aquatic life and habitats.

This would mean the need for environmental impact assessments (EIAs) to help identify and mitigate potential ecological damage. Using eco-friendly materials and construction methods, such as artificial reefs to support marine biodiversity, can further offset some negative effects.

Costs and funding

Understandably, underwater projects are inherently expensive due to specialised equipment, labour and materials. Securing funding for such high-risk ventures can be challenging, which is why public-private partnerships, government grants and innovative financing models would be required to provide the necessary capital for underwater construction projects.

An additional challenge - exposure to saltwater accelerates corrosion, while biofouling (the accumulation of organisms on surfaces) can damage structures and reduce efficiency. Anti-corrosion coatings, sacrificial anodes and regular cleaning would be essential to extend the lifespan of underwater structures.

Despite the challenges, the potential benefits of underwater construction are immense, offering transformative opportunities for various industries, as urban populations grow and land scarcity becomes a pressing issue. Underwater construction offers an alternative solution by utilising the vast unoccupied space beneath the oceans.

We already have underwater research facilities, such as aquariums or oceanographic labs, which provide scientists with unique environments to study marine life, climate change and geological phenomena. The Jules Undersea Lodge in Florida, for example, serves as both a research station and a tourist attraction, enabling direct observation of marine ecosystems.

Underwater hotels and restaurants are also offering unparalleled experiences, attracting tourists seeking novelty and adventure. Iconic projects like the Conrad Maldives Rangali Island’s underwater suite have demonstrated the profitability of such ventures.

Underwater construction is also playing a pivotal role in developing renewable energy sources such as offshore wind farms and tidal power stations. These installations support global efforts to transition to sustainable energy. As rising sea levels threaten coastal areas, underwater cities and floating structures also offer potential solutions. Designing submerged habitats can provide long-term resilience against flooding and land erosion.

Oil and gas platforms, such as those in the North Sea, exemplify large-scale underwater engineering. Subsea pipelines and deep-water drilling systems are critical components of these operations, highlighting the potential of underwater technologies in energy production.

As advancements in technology continue to push the boundaries of what is possible, we are seeing the emergence of robotic systems, including ROVs and autonomous underwater vehicles (AUVs), which enhance precision and safety during underwater construction. These machines can perform tasks such as welding, inspection, and material transport in hazardous conditions.

Materials such as self-healing concrete, corrosion-resistant alloys and graphene are also transforming underwater construction. These innovations improve durability, reduce maintenance costs, and enable more ambitious designs.

Digital twin technology is allowing engineers to create virtual replicas of underwater structures. These models provide real-time data on performance, enabling proactive maintenance and optimisation. Furthermore, underwater 3D printing has the potential to revolutionise construction by enabling on-site fabrication of custom components. This reduces transportation costs and accelerates project timelines.

Longer term, integrating renewable energy systems, such as solar panels and underwater turbines, can make underwater structures self-sustaining, reducing their environmental footprint.

The future of underwater construction

All this mean that the underwater construction industry is poised for growth as technological advancements and environmental imperatives converge. Innovative designs for submerged cities are gaining traction. Proposals like the Ocean Spiral by Shimizu Corporation envision self-sufficient underwater habitats powered by renewable energy.

Future projects must, of course, align with marine conservation efforts. Incorporating artificial reefs, sustainable materials and eco-friendly practices will be crucial to gaining public and regulatory approval. The shift toward renewable energy will further drive demand for underwater infrastructure. Offshore wind farms, tidal turbines, and underwater data centres are likely to proliferate.

That said, building underwater represents both a challenge and an opportunity for the construction and engineering industries. While significant obstacles - such as pressure, water leakage, environmental impact and costs - must be overcome, the potential benefits are transformative. From expanding habitable space and advancing marine research to enhancing tourism and supporting renewable energy, underwater construction holds the promise of a more sustainable and innovative future.

As we continue to push the boundaries of engineering and design, the underwater realm offers an exciting frontier that could redefine how we interact with and inhabit our planet. Through collaboration, technological innovation, and sustainable practices, the dream of building beneath the waves can become a reality.