Sargassum seaweeds were reported for the first time when European sailors crossed the North Atlantic at the end of the 15th century. Their presence there, in the middle of the North Atlantic gyre, is normal and even necessary for a number of species, as nursery habitat for small turtles, eels' spawning ground, etc. However, Sargassum have begun showing all over the Carribean and Gulf of Mexico coasts for some years now. There, they rot on the beaches, deplete the environment resources, block animals' paths or even navigation. 

However, they float in mats at the ocean surface, which are visible from space. Sentinel-3 OLCI sensor (ocean-color), or the geostationnary GEOS-16 ABI sensor, make it possible to spot them floating on the ocean. Then, physical oceanography models (assimilating altimetry), or even currents derived from altimetry and winds can be used to forecast where they should probably drift and be washed ashore. Studying their seasonal patterns and interannual variations could also be helpful in order to better understand and to lessen the damages they cause.