Seaweed develops in water everywhere, from the eternal glaciers to lagoons heated by the sun, from seas saturated with salt to the fresh water of our rivers. Yet we only know how to cultivate a few dozen varieties, at most. Incredibly diverse, seaweed could help to bring back balance in our ecosystems through a wide range of applications. Today a fast-growing global population, combined with climate, social and environmental crises, gives us compelling reasons to reconsider this forgotten treasure. The seaweed revolution is a fresh hope for tomorrow.