Learning How to Live with Risk—The Role of Co-Design for Managing City–Port Thresholds in Castellammare di Stabia, Naples, Italy

City–port thresholds are increasingly exposed to multi-risk, including climate change impacts, pollution, and obsolescence of buildings and infrastructure as well as socio-economic marginalization. This paper aims to understand what role co-design—and more generally collaborative planning processes—can play in enabling communities and institutions to learn how to live with risk when managing water, city–port interfaces, and coastal public spaces. To do so, this paper analyses the experience of a co-design workshop held in Castellammare di Stabia, in the Metropolitan Area of Naples, organized within the framework of the research MIRACLE and SPArTaCHus. The results of the workshop show that co-design can act as an effective instrument for developing strategies aimed at the regeneration and valorization of underused, abandoned, or polluted spaces in the coastal thresholds of City–Port areas—wastescapes—that are exposed to multiple risks. In these complex territories new methods are needed to understand, describe and interpret the fuzzy boundaries between the city and the port to collaboratively envision sustainable strategies for urban regeneration of coastal wastescapes.