The Riviera Maya on the eastern coast of the Yucatán Peninsula is world-renowned for its warm, turquoise waters and paradisiac beaches and Mexico’s most popular tourist destination. For the past couple of years, however, a new menace threatens to ruin the area’s charm: sargassum.

Sargassum is a genus of seaweed that grows in coral reefs. Some species are pelagic, meaning they never attach to the seafloor, spending their lifespans floating on the cyclic ocean currents instead. This plants usually provide breeding areas, food, and shelter for all manner of sea life… until too much of a good thing turns into an environmental disaster.

For the past three or four years, large masses of sargassum have made their way to the shores of different Caribbean countries such as Mexico, Barbados, the Dominican Republic, and Trinidad and Tobago. Many of these algae blooms have even been detected by satellites this year. These huge masses of seaweed clog up beaches, cause respiratory problems and affect marine wildlife.

When I heard about the problem while traveling in Tulum, I walked to the public beach to see the sargassum for myself. It had been several years since I’d been in the area and I wanted to compare my fond memories of a beach in paradise against the new realities locals couldn’t stop talking about.

As I drew closer to the beach, I could smell the rotting algae— from very far away. When I finally walked into the beach, I saw a line of sargassum covering the entirety of the beach near the waterline. The presence of clean-up gangs and heavy machinery made the beach look as though it was under construction. What’s more, more masses of sargassum floated in the ocean, and I couldn’t find a single space in the water that wasn’t overrun by algae, making swimming unpleasant.

This wasn’t the Tulum I remembered from four years ago when I first visited the area. Back then, the beach was pure white sand, with not a single speck of algae to be seen. What the hell happened?

I walked along the beach to where I saw a man raking in sargassum from the waters around his boat so that tourists don’t have to step on the seaweed, a Sisyphean task if ever there was one. After saying hello, he introduced himself as Eric, a resident of Tulum. He told me that sargassum has been arriving on the coast in visible increments for the past three years.

“It affects the wildlife and tourism. Look around you,” he said, gesturing at the deserted public beach (and from where I could see the famous cliffside pyramids of the Tulum Archaeological Zone), “it’s the high season and there are barely any people here. It’s affecting our community.”

The decomposed remnants of the sargassum turn the usually clear waters of Playa del Carmen brown. Yuck!

In places like Tulum and Playa del Carmen, local governments have hired work gangs and tractors to clean up the beach, hoping to alleviate the woes of local tourism. The beaches that get cleaned first are those of expensive resorts, further to the north.

Scientists offer several explanations for the sudden surge in sargassum: rising ocean temperatures and shifting ocean currents due to climate change, as well as the use of agrochemicals that find their way into the sea on the northern coast of South America. It’s clear this isn’t a natural phenomenon, but one caused by mankind’s indifference and irresponsibility—  when the sea gets a fever, it coughs out sargassum.

In the Riviera Maya, sargassum levels are at their worst during the hot summer months, when the Caribbean waters start to warm up. This also coincides with the high season for tourism, causing millions of dollars in lost revenue to communities that largely depend on tourism to make a living.

And it’s not only the tourism sector that suffers. The sargassum epidemic affects dozens of marine species. When it decomposes, it worsens the water quality, blocking coral reefs and suffocating fish. Turtles, in particular, suffer from changing environmental conditions. 

I walked some more along the beach to one of the stands where locals offer guided tours of the reef. There I talked to an older,  30-year resident of Tulum who said, “Sometimes the algae will be as high as your belly or your chest. It prevents the turtle hatchlings from finding their way into the ocean.”

While walking the beach in Tulum, one can observe cordoned-off areas about a meter in diameter marking turtle nests in the sand. When the sargassum piles up it creates a formidable barrier that blocks the beach and prevents turtles from laying their eggs. Furthermore, when turtles are successful in laying their eggs, the hatchlings emerge only to find their passage to the ocean is blocked by insurmountable piles of seaweed.

“Did this use to be a problem?” I asked.

“No! It was never a problem as far as I could remember. You’d always see a stray bit of seaweed here and there, that was normal. But we’ve been getting mountains of it for the past three or four years .”

Several days later, walking through Mamitas Beach in Playa del Carmen, I came upon an area where workers were removing the sargassum. The usually blue Caribbean waters had turned to a sickly brown, almost like sewer sludge— the fetid smell of the algae as it rots on the beach.

“Excuse me,” I asked one of the workers, pointing at the trickle of dark brown water winding its way along the sand into the ocean, “is that sewer water?”

“No! No! That comes from the sargassum.”

For the meantime, it seems the sargassum is here to stay. This is only one of a host of environmental disasters brought about by climate change. It’s not only real, but it has very real consequences you can see, touch and smell. 

We must solve the problems brought about by climate change if we’re to truly solve the problem. If we wish to preserve the oceans, each and every one of us has to pitch in. We can start by using and consuming less, promoting awareness about the problem, donating to climate change research, or many other things any one of us can do. We can try to scoop out every last bit of sargassum, but the ocean is vast and there’s plenty more where it came from.

As Eric told me as we observed the mounds of sickly-green algae beneath our feet, “We are the problem,” he then gestured out towards the sea, “and the solution is out there.”