Seagrass meadows are hidden underwater grass fields that protect the coast and offer shelter to many sea creatures. Seagrasses are flowering plants that evolved from the land back to the sea, and they now occupy the sea bottom in shallow waters along the coast all over the world. Human activities, such as fishing methods that rely on heavy nets that are dragged across the sea floor, put this important ecosystem at serious risk. In this study, we aimed to measure how seagrasses contribute to coast protection by trapping rock debris transported by the sea. Seagrasses reduce erosion of the coast and protect our houses and cities from both the force of the sea and from sea-level rise caused by global warming. Seagrasses do this by softening the force of the waves with their leaves, and helping sediment transported in the seawater to accumulate on the seafloor.