The objective is to improve the adaptation capacity of cities and densely built areas in the 2 Seas region by co-creating and implementing innovative climate change adaptation solutions with local stakeholders. This will result in an increased adaptation capacity of densely built areas in the 2 Seas region by at least 25,000 m3 as well as costs saving of 10 - 50% compared to the use of traditional adaptation investments. SPONGE paves the way for a wide rollout of these innovative participatory adaptation solutions to reduce the risks of and damage from urban flooding across the 2 Seas area at considerably lower costs.