For the past 15 years, Mexico has battled a severe seaweed problem, with vast quantities of a brown seaweed known as sargassum washing up on beaches along the Caribbean coast and taking a heavy toll on the tourism industry. The influx is part of a wider Atlantic phenomenon: since the first region-wide inundation in 2011, satellite monitoring has tracked a recurring band of sargassum — often called the Great Atlantic Sargassum Belt — stretching from West Africa across the tropical Atlantic toward the Gulf of Mexico and the Caribbean, with scientists linking its growth to nutrient runoff carried by major rivers such as the Amazon and to warming ocean waters. Even so, researchers have yet to find an effective way to prevent the seaweed from washing ashore or to reliably predict its movement. As the Mexican government works to manage the enormous volumes arriving each year, scientists are exploring potential uses for the algae, such as biofuel or fertiliser.

The scale of the problem is striking. As much as 9,000 tons of seaweed wash up on Mexico's beaches every day along the Caribbean coast, a region that depends heavily on tourist revenue. That dependence is significant: Mexico ranks among the world's most-visited countries, and the Caribbean state of Quintana Roo — home to Cancún, Tulum, and Playa del Carmen — receives the largest share of its international arrivals. Local governments across these major destinations are fighting to keep beaches clean, using industrial equipment such as diggers to clear the seaweed so visitors can continue using the beaches and swimming in the sea. It is a daily battle, and annual expenditure on sargassum management stands at around $2 billion — roughly equivalent to 11 per cent of local GDP.

Sargassum smells like rotten eggs and releases methane as it decomposes — the same gas that the biodigestion projects now under development aim to capture as an energy source. While it is not thought to significantly threaten public health, it can affect the health of vulnerable populations and of workers who are regularly exposed to the seaweed. Tourists, meanwhile, often avoid beaches where the seaweed washes up because of the smell, the inability to swim, and the weed's visual impact. This has driven many visitors to explore alternative destinations that have not yet experienced sargassum problems, such as Mexico's Pacific coast.

Government Response

In July, Mexico's President Claudia Sheinbaum announced a $115 million plan to combat surging sargassum in the Caribbean. The government plans to deploy two large ships to capture the seaweed before it reaches the coast. Mexico's navy is also expected to install 30 miles of containment barriers to trap the sargassum at sea in the most critical areas, including Playa del Carmen, Cancún, Tulum, Puerto Morelos, and Mahahual. Workers will continue to shovel up the seaweed that does make it to shore.

"The effort so far has been titanic, but we have to do more to prevent sargassum from reaching the beaches," Sheinbaum said.

Mexican authorities and the private sector currently have the capacity to collect almost 2,200 metric tonnes of sargassum each day at sea and on beaches. The government intends to increase this capacity to around 4,000 tonnes by 2027.

In addition, the government is partnering with Japan to tackle the problem. Japan will provide ocean-monitoring technology, specialised equipment including robotics and sensors, and financial cooperation as part of clean-up efforts.

Sargassum has become a major problem in several regions, with parts of the Caribbean and South Florida also reporting large quantities of the seaweed on their shores. Mexico is far from alone in its response: countries including the Dominican Republic, Jamaica, and Barbados have faced repeated inundations since 2011 and have trialled their own barriers and collection programmes. As part of the project between Mexico and Japan, researchers will explore the potential to convert the sargassum into commercially viable products — such as fertiliser, biofuels, building materials, and soap — which could help these regions regain access to their beaches.

From Nuisance to Resource

Mexico's Environment Minister Alicia Barcena said that out of almost 200 sargassum-related projects, at least 11 had the potential for scaling up industrially, while 39 were already making products, including fuel, fertilisers, laminates, and bioplastics used to produce sandals.

In July 2025, the Quintana Roo state government announced plans to develop a new facility to monitor and manage Mexico's sargassum and eventually convert it to biofuel. A Dutch consortium will finance, construct, and operate the Sargassum Centre, which aims to develop new technologies for the biodigestion of sargassum and organic waste to produce biomethane. If successful, it could provide the blueprint for other regions dealing with sargassum to follow.

The chemical composition of the sargassum found along Mexico's Caribbean coast could also make it suitable for use as an agricultural input. A 2026 assessment by the Inter-American Development Bank (IDB) and the Mexican Institute for Sustainable Fisheries and Aquaculture Research studied the seaweed closely to better understand its potential as an economic opportunity rather than a burden.

Researchers from the Technological Institute of Santo Domingo and the IDB have developed methods to produce energy from sargassum while separating the arsenic contained in the algae. That step matters because sargassum readily accumulates arsenic and other heavy metals from seawater, a characteristic that must be managed before the algae can be safely used in agriculture, construction, or fuel. Mexican government departments and university research centres are also exploring the potential to use sargassum as an organic construction material to produce blocks, bricks, paving stones, and asphalt mixtures.

Mexico has invested heavily in cleaning up the huge influx of sargassum over the last decade, even as satellite tracking has recorded record volumes in the Atlantic belt in years such as 2018 and 2023. Now, the government and private sector hope to effectively analyse the brown seaweed to better understand its potential as a biofuel, fertiliser, or other product — and to develop economic opportunities from something that has so far been seen as a plague that disrupts regional tourist activity and revenue. Whether pilot projects such as the Sargassum Centre can scale into an industry capable of absorbing the volumes that arrive each season is the question other affected regions are waiting to see answered.

By Felicity Bradstock for Oilprice.com