Record seaweed blankets Mexico’s Caribbean coast, threatening tourism and the environment
Written by: Iñigo Alexander and Paola Chiomante
TULUM, Mexico, July 28 (Reuters) – Brown, smelly seaweed is arriving in record waves on beaches along Mexico’s Caribbean coast, causing the closure of top tourist destinations and causing mounting economic damage to hotels, restaurants and shops.
The unprecedented mass of sargassum, a brown seaweed that drifts in vast sheets across the Atlantic and is pushed toward the Caribbean coast by ocean currents in the spring, has prompted the federal government to draft an emergency plan to combat the problem.
In the eastern state of Quintana Roo, a tourist hotspot that is once home to crystalline beaches like Cancun and Playa del Carmen, environmental officials predict 119,000 tonnes of sargassum will wash ashore by the end of the year, surpassing last year’s record of 96,000 tonnes.
“Higher temperatures will give you more sargassum,” said Brian Barnes, a research assistant professor at the University of South Florida College of Marine Science who studies the phenomenon, adding that the combination of nutrients and long days of sunlight also play a role.
Sargassum stranded on the beach begins to rot quickly and often emits a fouler odor than rotten eggs.
“The decline in tourism is extremely serious,” said Tulum Councilman Eugenio Barbachano, blaming the sargassum epidemic. “The low season is not just low, it’s critical.”
Workers line many beaches along Quintana Roo’s Riviera Maya, knee-deep in seaweed, shoveling clumps of sargassum along the shoreline to polish the shore; Possibly a Sisyphean task as some of the season’s worst months are still to come.
Quintana Roo Governor Mara Lezama says sargassum management costs the state roughly 11% of GDP, or about $2 billion a year, while the Riviera Maya hotel association estimates the cost of combating seaweed at about $150 million annually.
Yet in recent weeks, dozens of Quintana Roo beaches have been put on red alert for algae, and some have even closed. “Extreme” levels of sargassum were detected on 92.5% of the state’s beaches in late June, according to a local monitoring network.
“Quintana Roo is a state selling beaches, blue sea and water activities,” said local tourism service provider Carlos Solis. “It affects everything.”
Marine scientists also warn that rotting seaweed deprives underwater plant life of sunlight, reduces biodiversity and can even leach arsenic and other heavy metals into the sand.
Workers who have shoveled sargassum from beaches in the past have reported itchy and burning skin, headaches, fatigue and nausea associated with the algae, according to a 2025 study published in a scientific journal.
To combat seaweed, the Mexican Navy has deployed a sargassum combat fleet consisting of 11 dedicated coastal ships, an amphibious sargassum harvester, 18 support boats, two barges and four unmanned aerial vehicles. It also installed more than 9,000 meters (29,500 feet) of protection barriers to protect the beaches.
The government will present a revised response plan on July 30 in the hope of better tackling the problem.
Brian Lapointe, a research professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, said the Caribbean needs a system that combines “satellite observations and modeling predictions with targeted response before sargassum reaches the coast.”
Some tourists brave the seaweed-covered waters.
“I went swimming today,” said Swedish tourist Wendy. “I expected worse.”
(Reporting by Iñigo Alexander and Paola Chiomante; Additional reporting by Anna Portella and Hugo Monnet; Editing by Emily Green and Lincoln Feast.)
