Ever since the mega project of cleaning the Seine in preparation for the Paris 2024 Olympics gained world-wide attention, a global movement is inspiring urban policymakers and to reclaim urban waters in becoming a ‘Swimmable City’. As in many of these cities, the city of Rotterdam, the Netherlands, sees a growing demand for reconnection with the waterfront, urban living quality and resilience to urban transitions, while simultaneously facing the effects of climate change on the city and its residents first-hand. The Municipality of Rotterdam has shared their ambition to develop future urban bathing sites in open-air waters, among which the inner city harbours. However, the urban complexity of these locations goes hand-in-hand with practical and systematic implementation challenges. This research is framed by an urban systems-based approach, in order to identify the place- and actor-related challenges and opportunities in their urban system nature, for three typologies of (floating) urban bathing structures defined in this study (The Free Style; The Protected Plunge; The Dip in a Bowl). Taking lessons from case study interviews with three respective (inter)national urban bathing typology examples (Marineterrein in Amsterdam, La Baignade Villette in Paris, The Floating Pool Lady in New York City), overarching physical and non-physical challenges were overcome by flexible design, creative governance and justification in connecting other local societal agenda’s such as the accessibility of public space, improving water quality and swimming programming for local communities. Comparing these lessons with identified challenges and opportunities for Rotterdam’s Spoorweghaven, Coolhaven and Persoonshaven, based on case study interviews with local project managers, the conclusions of this research are presented as recommendations for civil servants on how to approach the development of future urban bathing sites. Not only for the City of Rotterdam, but all cities who have the ambition to become ‘swimmable’.