San Andrés Island, Colombia

12°35’13.7″N 81°41’00.5″W
Our pilot reef – El Castillo


Developed in Zürich through collaborations with ETH Zürich and ZHdK, our first full prototype  – rrreef 1.0 – was implemented in September 2021 on the coast of San Andrés Island, Colombia, where over 90% of all jobs depend on coral reefs, and reef destruction has taken its toll.


rrreef 1.0 was built together with 11 workshop participants in collaboration with our local partner NGO Corales de Paz and the valuable support of Conservation International Colombia, the Colombian Ministry of Environment, the Colombian Navy, and the local environmental authority CORALINA.


The 228-brick reef is our most important project to date. After material and structure field tests, it is our first proper reef. Financed by a crowd of supporters, this project is not only a scientific experiment, but also here to connect people. Amongst each other and with coral reefs.

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Reef-building workshop

In our hands-on in-water reef-building workshop with Corales de Paz, participants got insights into coral ecology, different approaches to coral restoration, and ecosystem rehabilitation. They learned why structure matters for coral larvae settlement and growth, and about appropriate design, logistics, and scientific underwater methods. After learning critical background information on reef restoration best practices, we introduced participants to our new approach of passive, structure-based habitat regeneration.

They really got their hands on it and learned how to safely build a new reef structure underwater, acquiring in-water skills such as handling heavy gear, lift bags, ropes, and of course our rrreef brick system. This included construction of the reef foundation, scouting and preparing the reef site, implementing and anchoring the new structure underwater, and finally using coral fragmentation and transplantation techniques to outplant first corals onto the new reef. Further our participants experienced the process of selecting and evaluating donor, nursery, and transplantation sites, and maintaining and monitoring nurseries and reef structures.



How we monitor success

rrreef 1.0 is a scuba attraction – the locals call it “El Castillo” – and a valuable data source for us. Our multi-year scientific monitoring plan includes bi-annual assessments of the structural integrity, fish diversity, diversity of cryptic animals, recruitment of young coral to the structure, and of the health of our transplanted corals.

Around the year, local dive operators are contributing video footage based on our citizen science initiative. These efforts all help to establish a solid database and we can test our hypotheses on the biodiversity-enhancing functions of our reef system and geometric dependencies of coral survival. After just three months, in December 2021, 38 different fish species were feeding on and hiding in our reef, and fish richness approached that of the natural reef already.