A short documentary film related to the environment of coastal cities / mega cities highlighting the vulnerability of these large settlements due to their high demography and to the impacts of marine related hazards (coastal erosion, storm surges, tsunami, forecasted sea level change) as well as the environmental footprint of large coastal cities on marine ecosystems (degradation of coastal habitats, waste management, emissions, pollution, public health impacts). The film will also emphasise the need for sustainable coastal cities to build their planning policies on science based information and products such as the ones promoted by IOC (coastal and ocean monitoring systems, hazards warning systems and preparedness, integrated coastal management and marine spatial planning).