Seaweed surge: Mexico’s Riviera Maya faces worst sargassum season in years

As sargassum season officially begins along Mexico’s Riviera Maya, local authorities are sounding the alarm for what could be one of the largest seaweed invasions in recent years.

As reported in Mexico Daily News, seaweed has begun arriving earlier than usual this year, and Esteban Amaro, head of the Sargassum Monitoring Network in Quintana Roo, warned that 2025 could bring an especially severe outbreak.

“We are expecting more intense and more frequent arrivals along the entire coast,” he was quoted as saying.

According to Amaro, satellite data shows that this summer’s sargassum levels are expected to exceed those of the past three years. “Last year, we collected more than 40,000 metric tons, and we will easily surpass that figure this year,” he told the outlet.

While sargassum plays a valuable ecological role in the open ocean—providing shelter and nutrients for marine life—its accumulation along shorelines poses serious threats.

Once it washes ashore in large amounts, it begins to decompose, releasing hydrogen sulfide gas that smells like rotten eggs and can harm marine ecosystems, coral reefs, and even human health.

Typically, sargassum season peaks from April or May through August, but it can linger into November.

Last year, Quintana Roo didn’t officially close seaweed season until November 14. Since large-scale influxes began in 2011, dealing with the seaweed has become a growing challenge for officials, especially in tourism-reliant areas.

Tulum, a major tourist hotspot, collected 50 per cent more sargassum during January and February this year than in the same months of 2024, according to Zofemat (the Federal Maritime Terrestrial Zone).

By mid-April, Playa del Carmen, Othón P. Blanco, and Puerto Morelos had jointly removed over 10,200 metric tons of sargassum, according to the state’s Ecology and Environment Ministry.

Governor Mara Lezama officially launched the 2025 sargassum season response on April 15, highlighting a coordinated plan to manage the situation.

The initial phase involved installing nearly 9,500 meters of offshore barriers at key locations to trap the seaweed and funnel it to designated collection points.

Amaro emphasized that while these barriers are vital, unpredictable weather conditions could drive massive new influxes.

To bolster the response, the Navy has activated a monitoring operation, using 11 large and 22 smaller vessels to detect and gather floating sargassum before it reaches the beaches.

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