Given the flooding risks emerging from climate change, the chapter explores the amphibious transformation through counterproposals to terra-centric urbanization. It addresses how and why cybernetics-based designs for Tokyo Bay in the 1960s experienced long-lasting marginalization but shaped the present ecomodernist approach to climate-resilient sea surface urbanization, like the United Nations’ “sustainable floating city” project. Ecomodernism is an environmentalist “school” and focuses on technologically decoupling socio-economic development from resource use and environmental degradation. The chapter argues that these 1960s’ cybernetic designs were counterproposals to the “tools of terrestrialization,” like dams, seawalls, and industrial-scale land reclamation, which the Age of Coal’s access to affordable energy had globally enabled. Architect Tange Kenzō’s and designer Buckminster Fuller’s teams devised artificial communication systems that replicated biological processes, returning urbanization’s attention to the adaption to aquatic conditions. The cybernetic designs sought to decouple urban growth from pressure on ecosystems, turning them into forms of proto-ecomodernism.