Rotterdam Reef Successfully Installed for Nature and Shoreline Protection

Delft start-up Reefy is building a reef in the river Meuse for biodiversity and shoreline protection.

Rijkswaterstaat, the Municipality of Rotterdam, Boskalis and Reefy are testing the Reefy artificial reef system to support nature restoration and conservation efforts in the tidal area of the river Meuse, as part of the “Groene Poort” or “Green Gate” project. After careful preparation and in close collaboration with all the partners, 17 Reefy modules were assembled underwater by Boskalis in under 3 days. The artificial reef is approximately 25 meters long and 3 meters high which makes it possible to see its top layer during low tide.

Next to the four consortium partners mentioned below, this pilot project was made possible thanks to invaluable technical advice and support of PortXL, Rotterdam Zoo Blijdorp, Burgers Zoo, TU Delft and Deltares.


About the Partners:


Reefy is a young eco-engineering company from Delft, the Netherlands that combines biology and hydraulic engineering to develop nature-inclusive solutions for coastal protection and offshore wind projects.

Reefy's ReefBlocks are massive “Lego-like” blocks, which have been hydrodynamically designed and tested in the Deltares wave flume. By assembling these blocks underwater, a stable structure is formed that dissipates wave energy and also creates an underwater labyrinth where fish and other species can shelter and breed. The blocks are made of sustainable concrete with a special texture on the surface. With this, the start-up aims to stimulate all kinds of biological growth such as oysters and mussels to create a living layer that promotes biodiversity and can grow with sea level rise, requiring less maintenance. Next to the Rotterdam Reef project, Reefy is working on several international pilot and demonstration projects in the Caribbean, Central and North America with a range of products both for coastal protection and offshore wind.

“We need to rethink marine infrastructure and include the right conditions for letting nature thrive. It is important that water and sediments can go through breakwaters, then those appropriate conditions will allow ecological foreshores to develop that can grow with sea level rise. The ReefBlocks provide this and the necessary complexity to boost life underwater. These eco-engineering solutions will be cheaper to maintain compared to traditional structures in the face of climate change,”said Jaime Ascencio, CEO and Co-Founder of Reefy.

“The ecological development on the reef will be continuously monitored by us to see effects on the total improvement in ecosystem services, compared with the conventional solutions. Before the installation, the benchmark biodiversity measurements were taken by Reefy, and we expect the first ecological results of this transformational coastal defense project in a few months,” said Leon Haines, CTO and Co-Founder of Reefy.

The history of Reefy

The Delft start-up Reefy was founded by Jaime Ascencio and Leon Haines. Ascencio worked as a Business Developer in Mexico and the Caribbean region, where he sought sustainable solutions for resorts against coastal erosion. The current artificial reefs on the market turned out to be unstable if used as breakwaters. To find a solution, he left for TU Delft to follow the Master's in Coastal Engineering. Haines is a marine biologist who, after studying Integrated Coastal Management / Marine Biology, spent five years working on coral reef restoration projects on islands in Thailand, the Maldives and Indonesia.

The Groene Poort (Green Gate): City of Rotterdam and Rijkswaterstaat (Dutch Ministry of Infrastructure and Water Management)

Since the end of 2013, the City of Rotterdam, Rijkswaterstaat, the Port of Rotterdam and the World Wildlife Fund have been working together on sustainable, nature friendly riverbanks in the river Maas (river Meuse) in the densely populated and industrialised area. The project is called ‘De Groene Poort’ or 'Green Gate'. To keep natural riverbanks in place and to protect them against the waves of ships and current, breakwaters are needed to create a foreshore. Rijkswaterstaat and the City of Rotterdam are looking for more sustainable solutions for this than the usual rock or stone dams. By testing these reef innovations in collaboration with Reefy, the City of Rotterdam and Rijkswaterstaat hope to find a resilient and sustainable solution to restore the natural values in the tidal area of the Maas River. Besides the Groene Poort, the program River as a Tidal Park is in progress to realize tidal parks in the delta. The City of Rotterdam is one of the partners in this program.

“To improve the water management and quality, we are constructing various types of breakwaters along the riverbanks of the Nieuwe Waterweg. This creates a sheltered area that is favorable for (migratory) fish, birds and aquatic plants. We use sustainable (recycled) and innovative materials for the breakwaters. We are happy to give space to a pilot such as this one that has both hydraulic and ecological value and is produced sustainably,” said Sander de Borst, Technical Advisor, Rijkswaterstaat (Ministry of Infrastructure and Water Management).

“The reef helps us to improve biodiversity, protect against flooding and make waterfronts more attractive with tidal nature. Close cooperation with a startup, a corporate and a water authority gives added value for all of us. Together we will improve the nature of the river delta in Rotterdam,” said Joep van Leeuwen, Senior Consultant Urban Development City of Rotterdam.


As an international leader in dredging, offshore wind, and maritime services, Boskalis is always looking for sustainable alternatives to implement in projects all over the world. Boskalis' Artificial Reefs Program supports innovative start-ups in developing products to achieve large-scale positive impact. For the test set-up, Boskalis helped install the project in the Nieuwe Waterweg with large equipment and expertise. This project is also Boskalis' fourth artificial reef knowledge development project under the Artificial Reefs Program, with previous placements also in Monaco, Kenya and Panama.

“It’s always a special feeling when something that you have worked on for so long can be put into practice and tested in the real world. That step is not the end goal, only the beginning of realising large scale application of these modular artificial reefs,” said Paul Peters, Program Lead Artificial Reefs Program of Boskalis.


In 2021, the City of Rotterdam and Boskalis gave Reefy so-called 'golden tickets' to participate in the maritime accelerator program PortXL. In this program, startups and scale-ups are connected to potential customers and network to test and market innovations. The Rotterdam Reef project, that aims at the chain from production of blocks to monitoring of the reef, has arisen from initiatives from all parties to stimulate innovation.

Diergaarde Blijdorp, TU Delft and Burgers Zoo

Blijdorp Zoo helps innovative companies by creating space as a testing ground. In collaboration with Delft University of Technology, Blijdorp offers facilities and guidance for start-ups to develop new technologies. Reefy has worked closely with the Oceanium in Blijdorp and Burgers Zoo in Arnhem to develop their technology. At the visitors’ side in the Science Aquarium in Blijdorp, it is possible to see a scale model of the reef installed in the Green Gate. The model is used to educate visitors about the role of artificial reefs in wildlife restoration and importance of reefs for shoreline protection.


Deltares is the independent knowledge institute for applied research in the field of water and subsurface. Throughout the world, Deltares works on smart solutions, innovations and applications for people, environment and society.

Reefy has been collaborating with Deltares in the technological development and successfully tested ReefBlocksTM in the Deltares state-of-the-art wave flume in simulated hurricane conditions.

“The Reefy Living Breakwater has been tested in our experimental facilities, showing stability and wave attenuation under hurricane conditions. We see the potential in the field and are looking forward to further collaboration.” – said Marcel van Gent, Manager Coastal Structures and Waves, Deltares/TU Delft.