The Intergovernmental Panel on Climate Change (IPCC) recently evaluated large floating structures as an experimental yet noteworthy strategy for urban climate adaptation, advancing urban elements to the surfaces of aquatic bodies. In 2021, the Global Center on Adaptation, located in Rotterdam, Netherlands, moved to its floating office, exemplifying floating adaptation. Currently, UN-Habitat, the metropolitan government of Busan, South Korea, and the ocean technology company Oceanix are collaborating on a large floating settlement designed to adapt to sea level rise and enhance the city’s flood resilience. Floating structures for urban development have emerged as a tool in the repertoire of technology-focused environmentalist thinking. Focusing on the question of social acceptance, this paper explores how different forms of environmentalist thought have either legitimized or delegitimized the use of floating structures as a form of urban development from Buckminster Fuller’s Triton City in the 1960s to the present day. Based on examples from the 1960s–1970s and from the 2010s–2020s, this paper argues that floating structures, including residential ones, can serve as tools in an advance strategy in places where local conditions enable their installation as part of urban flood risk management and climate adaptation. However, conflicts between technology-focused and techno-critical environmentalist “schools” of thought, clashes over incompatible aesthetic perceptions of floating structure designs and urban waterfronts, and particularly right-libertarian views of floating structures as mobile means to establish new legal frameworks beyond governmental environmental legislation’s reach continue to impact their political and consequently market and community acceptance. The success of floating structures in urban development therefore hinges not only on engineering and architectural considerations but also on situating them in environmentalist and socio-economic development strategies.