This summer, Mexico's Caribbean coast has looked nothing like a dream holiday destination. Dozens of tons of algae have been covering the turquoise waters and soft sandy beaches of Cancun, Playa del Carmen and Tulum. It's sargassum - a floating and mobile algae that breeds rapidly and is invading the Caribbean at an alarming rate. Scientists believe it's the result of rising ocean temperatures and pollution from fertilizer. But could the algae actually come in useful? Our correspondents report.
A programme prepared by Patrick Lovett and Gaëlle Essoo.