Sargassum (Sargassum sp). Volunteers collecting waste (plastics, ropes,...) dragged by the mass of algae. The genus Sargassum is characterized by having gas vesicles known as “aerocysts” that provide them with buoyancy. Thanks to these “balls” of gas, some species of sargassum are able to remain floating on the surface of the ocean for months and the currents end up accumulating them, forming immense aggregations similar to floating islands. In the North Atlantic Ocean is the Sargasso Sea, which receives its name precisely because the presence of these gigantic aggregations on its surface is common. It serves as food, shelter and breeding area for many marine animals, such as crabs, turtles, shrimp and seabirds. At some times of the year it can appear stranded in large numbers on beaches exposed to the current and/or wind. On some occasions, it may appear mixed with drifting garbage such as ropes, small talk, bottles,... Playa Grande, Punta de Abona. Tenerife, Canary Islands.