In 2025 the majority of the world population will live in flood prone delta cities. Delta City Rotterdam, with one of the biggest ports in the world, is dealing with the consequences of climate change in a very pro-active and smart way, turning challenges into opportunities. The RCP Rotterdam Climate Proof program aims at making the city completely climate resilient by 2025, by building multifunctional flood protection and innovative water storage for urban drain water. But also by kicking-off a Rotterdam Adaptation Strategy RAS, by using new smart technologies like Apps and serious gaming, and by redeveloping and revitalizing its old city ports areas with attractive waterfronts. At these waterfronts, where education of future generations is combined with innovative and sustainable development of businesses, best practices are showcased to make the city more attractive, to add economic value and to create resilient communities. This knowledge and experience is shared with other delta and coastal cities in the world, in the ‘Connecting Delta Cities’ global network, and with the Rockefeller Foundation 100 Resilient Cities initiative. This article explains that dealing with climate change in a pro-active and smart way creates opportunities for attractive, resilient and economically strong delta cities of the future.