In 2011, 2014, 2015, and in 2018, thousands of tons of pelagic sargassum seaweed, referred to as sargassum influxes, have piled up to 3 metres thick on beaches and in the nearshore waters of many Caribbean states and territories. These events have triggered much consternation regionally about state, civil society and private sector capacities to cope and adapt. There has been concern, including among inter-governmental organisations, about long-term implications for the fisheries and tourism sectors especially, given that such events seem to be a ‘new normal’ due in part to climate change and variability. The interested parties also realise that sargassum influxes may offer opportunities ranging from agriculture to manufacturing, if the region can support innovation and entrepreneurship. Discussions on marine and coastal policy, management, science and technology at local, national and regional levels about how to deal with a sargassum influx as a new biological natural hazard with the potential for disaster, or as abundant raw material with potential for windfall gains, have considered issues of biodiversity, coastal management, fisheries and tourism livelihoods, foreign exchange earnings, public health, innovation and entrepreneurship opportunities and more.