Urban Ocean is a capacity-building and accelerator program to end ocean plastic pollution and build more resilient communities in cities. Urban Ocean champions circular economy principles, builds awareness of ocean plastic, assesses waste management systems, and supports cities to develop projects that address the interrelated challenges of ocean plastics and resilience. Since 2019, the program has been jointly implemented in twelve cities by Resilient Cities Network, Ocean Conservancy and The Circulate Initiative using CAP as the science foundation.