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Puerto Morelos, Quintana Roo, Mexico — Every morning, a small boat named “Lucero” remains anchored, floating alone next to a deserted dock in Cancún. No one asks about it. No one boards it. The days of reef excursions, of tourists excited to experience the Mexican Caribbean from the sea, are long gone. What was once a promising business has now become a silent symbol of an environmental crisis that grows year after year: the massive arrival of sargassum.
The Mexican Navy (Semar) announced in July 2025 that it had surpassed historical records for sargassum collection along the Caribbean coast. Since 2019, the accumulated figure has reached 290,000 tons off Quintana Roo alone, an unprecedented volume that highlights the magnitude of the phenomenon seriously affecting the region, where the decline in tourism is beginning to have alarming economic effects.
For the captain of Lucero, Juan Hernández, the boat is not just a means of support: it’s a symbol of what can still be saved.
Hernández, a 59-year-old Mexican, spends his days sitting on the edge of the dock, watching his vessel as if waiting for a miracle.
“I used to take three or four trips a day,” he says nostalgically. “Now, if I’m lucky, I take one a week… if anyone dares to go into the water.”
The reason is obvious — a thick layer of sargassum covers the coast, giving off a fetid smell of decomposition.
This phenomenon, which has severely affected the entire state of Quintana Roo for more than a decade, has intensified in recent years due to factors such as climate change, the increase in nutrients in the ocean from agricultural fertilizers and wastewater, and rising temperatures in the Atlantic.
In the aforementioned state of Quintana Roo – located on the Yucatán Peninsula – there are world-famous beaches, including Cancún, Puerto Morelos, Tulum, and Playa del Carmen; all of these beaches are affected by this major natural threat.
But beyond the tourist and visual impact, sargassum represents a direct threat to the marine ecosystem and the local economy. Our interviewees emphatically stated that “if the problem persists, they will have to choose other destinations to vacation with their families.”
A Floating Environmental Problem
Sargassum is neither an invasive algae nor an exotic species. In fact, it is part of the Atlantic’s marine ecosystems. However, its uncontrolled proliferation—fueled by human activity—has transformed what was once a natural presence into a regional problem.
Research from the Institute of Marine Sciences and Limnology (UNAM) indicates that massive accumulations of sargassum block the sunlight that seagrass needs to survive, alter the oxygen balance in the water, and suffocate corals and marine fauna when deposited in large quantities.
When they reach the coast and decompose, the algae emit gases such as hydrogen sulfide, generating an unpleasant odor that scares away tourists and can cause respiratory and skin irritations in sensitive people.
In an interview, we spoke with Dr. Ligia Collado-Vides of Florida International University (FIU), a marine botanist who has dedicated her career to studying this phenomenon in the Mexican Caribbean.
“Sargassum is a genus with more than 350 species,” Collado-Vides said, “and only two are causing this massive growth.”
Why is it different now?
“Because we have a new Sargassum Sea called the Great Atlantic, near the Sargassum Belt that grows between Africa and Brazil, and it continues with the currents that come from the equatorial zone toward the Caribbean,” Collado-Vides explained. “In the Caribbean, it acts like a sieve, and everything that remains downwind is left there, and they are the first recipients.”
Why do we have a much bigger problem?
“This is a planetary problem,” said Collado-Vides. “We have higher temperatures, we have much more carbon in the water, and those of us who are studying the impacts of nutrients are trying to understand what is happening and the climate changes they generate.”
Tourism in Decline
The tourism sector—the economic engine of the Mexican Caribbean—is one of the hardest hit. Hotels, restaurants, tour operators and small boats like Juan’s face constant cancellations. Visitors, unable to find the crystal-clear waters promised in brochures, are seeking other destinations.
“Last year, I had to sell one of my boats to survive,” Juan confesses. “This year, if things don’t improve, I’ll have to sell this one too.”
Many tourism service providers have opted to invest in anti-sargassum nets and floating barriers, while others promote tours in less affected areas or eco-tours focused on environmental conservation. However, the struggle is uneven.
What is being done?
Various sectors have proposed solutions ranging from mechanical harvesting at sea to transforming sargassum into biofuel, useful materials, paper, food or construction materials, following strict regulations.
However, according to Dr. Francisca Elmer, a German resident of Mexico, “the lack of a comprehensive national strategy and the limited coordination between government levels, businesses, and the scientific community make it difficult to implement effective measures.” Elmer also explained that sargassum is here to stay if the root causes, marine pollution and global warming, are not addressed.
“We can mitigate its effects, but we need political will and social awareness,” Elmer said.
Meanwhile, Juan Hernández isn’t giving up completely.
“I keep coming back every day because I have hope that the sea will recover. But I also know that won’t happen on its own. We need to take care of what we have left,” says the sea lover with great emotion.
