Sargassum algae is seen on a beach in Cancun, August 11, 2015. The Sargassum algae contains biting sand fleas and releases a pungent smell as it decomposes. It has choked beaches in resorts throughout the Caribbean including Cancun this season, prompting local authorities to launch a large-scale clean-up operation. REUTERS/Edgard Garrido PICTURE 7 OF 34 FOR WIDER IMAGE STORY 'EARTHPRINTS: CANCUN'SEARCH 'EARTHPRINTS CANCUN' FOR ALL IMAGES