As it decays, the seaweed doesn’t just vex sunbathers; it also kills marine life. While the amount of floating seaweed in the belt waxes and wanes with the seasons, its peak amounts have grown over the years. This can be beneficial as seaweed can be used to remove toxics from water, but hazardous in products made from the seaweed. “When you grow seaweed in [seawater], certain rare earth elements … get bioconcentrated in the seaweed by a factor of 10,000 to a million, depending on the seaweed, and depending on the elements,” says Huesemann. Other technology may someday help gather the seaweed too, like electric self-driving tugboats that can tow heavy bags of seaweed to biorefineries onshore, says Roberson.