New strategies for coastal protection are required to cope with rising sea levels caused by climate change. They are aimed at the sustainable development of coastal areas in the face of intensification and changes in land use. One promising approach is the development of nature-based solutions (NbS), which complement the safety level of the technical infrastructure. However, NbS lacks widespread and large-scale implementation. To overcome this deficit, co-design concepts are needed that combine experience from science and practice. In this paper, the approach of a coastal real-world laboratory (RwL) is presented and discussed, which deals with the integrative design of ecosystem-based coastal protection. Strategies of RwLs are applied for the first time in a coastal context along the German North Sea coast. We have found that the concept of RwLs is suitable for transdisciplinary coastal research, even if adjustments in the spatial reference level or flexibility in terms of location and time of experiments are necessary. A well-founded analysis of actors is essential in order to specify participatory processes and levels of interaction. A criteria-based cooperative selection of RWL sites helps to uncover and resolve conflicts of interest in order to create trust between science and practice. Taking into account site-specific characteristics and the needs of practitioners, our coastal RWL provides a mutual learning space to develop and test NbS as a complement to technical coastal defence.