Each year, the world throws 8 billion metric tons of plastic into the ocean, about a dump truck every minute. Some washes up on beaches, some sinks, and the rest floats to the surface, where currents sweep it into giant rafts of garbage. Over time, chopping waves and beating sunlight break those plastics down into microscopic particles—which conservation groups worry pose a real threat to marine life and the people who eat it. But there are ways to pull those plastics out of the sea.