Portcities are at the forefront of transitioning towards a green and circular economy (UN 2019). Especially in transforming former port areas, the integration of nature-based solutions(NBS) is crucial to increase natural capital and support social- and economical ecosystem resilience. This requires further mainstreaming of NBS in urban design and urban planning practices. In this thesis scenario research-by-design methods are used to explore their implications for the Waalhaven.