Five thousand miles long, 400 miles wide, and over six million tons, a massive bloom of seaweed is drifting toward Florida and the Gulf of Mexico.

According to ABC News, scientists at the University of South Florida, with the help of the National Aeronautics and Space Administration, have been tracking the bloom of sargassum, a type of brown seaweed, using satellites. Originating in the Atlantic Ocean, the bloom is approaching the Caribbean Sea and the Gulf of Mexico, posing a threat to beaches across the Gulf, including tourism-centric Florida.

When the bloom hits a beach, it can pile one to two meters high on the shoreline and clog swimmable waterways, according to scientists. If the seaweed is not removed from the beach quickly, it will begin to rot, emitting hydrogen sulfide gas, most associated with the smell of rotting eggs that can irritate skin, eyes, and the throat, as well as make breathing difficult for those with asthma.