Threats to our ocean are climbing both public and political agendas. The BBC’s Blue Planet and Netflix’s Our Planet brought home how plastic pollution, climate change and other human activities are damaging marine life. The UN ‘Decade of Ocean Science for Sustainable Development’ begins in 2021; special ambassadors and envoys have been appointed to mobilise action. But for real impact, positive intentions must deliver concrete initiatives that protect the ocean and involve the coastal communities whose livelihoods depend on it. Marine protected areas (MPAs) are a promising example. With a rigorous science-based approach, effective management and the right investment, MPAs are one of our best tools for protecting marine biodiversity.