“Getting too close to and spending too much time along the shoreline means burning my eyes and lungs, and per my local physician, perhaps untold lasting damage,” wrote Surfer correspondent Owen James Burke reporting from the Lesser Antilles, back in May.
And what was Burke referring to? Ancient Napalm deposits in Asia? Monsanto pesticide runoff in Maui? Nope, he was reporting on the growing issue of sargassum onshore buildup at his homebreak. Sargassum is a free-floating brown macroalgae that drifts on ocean currents in vast rafts, sometimes the size of football fields. The seaweed itself is native to the Atlantic and has always existed in the Sargasso Sea, and in the open ocean is a genuinely valuable habitat, providing nursery grounds for mahi mahi, sea turtles, and dozens of other species.
However, once on land, though, it decomposes and releases toxic gases including hydrogen sulfide and its distinctive rotten-egg smell. In the water, the thick mats can slow or snag as surfers paddle back to the lineup. Burke recalled how face-planting into a mat at the end of an otherwise clean right-hander became a routine, if comic, and toxic hazard. It might be one of the biggest issues facing surfers and users of coastlines of the Gulf of Mexico, Caribbean Sea, and eastern Atlantic Ocean.
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The bad news is that this is a relatively new phenomenon. It’s called the Great Atlantic Sargassum Belt (GASB), an interconnected mass of the stuff that’s been forming and growing since 2011. It now stretches across the tropical Atlantic from West Africa to the Gulf of Mexico. 2025 set the biomass record at 37.5 million tons, and researchers expect 2026 to exceed it. By the end of May 2026, an estimated 28.9 million metric tons were already recorded across the Atlantic, with the largest concentration east of the Leeward Islands and significant coverage between Puerto Rico and South America. USF’s Optical Oceanography Lab officially classed 2026 as a “major sargassum year” with real potential to be the biggest on record.
Floridian and Gulf surfers won’t find that surprising. They are used to surf sessions involving paddling through mats, dodging decomposing piles on the beach on entry/exit, and dealing with the fart stench on the sand between sets. If that wasn’t fun enough, the mats often carry small stinging organisms like jellyfish larvae that irritate on contact, similar to the feeling of surfing in sea lice.
In Miami, sargassum removal is now a full annual budget line, accounting for $9 million of the city’s $11 million total beach maintenance budget every year. A Woods Hole Oceanographic Institution study estimated Florida alone loses around $5 billion a year to Sargassum’s impacts.
Local surfers will increasingly need to deal with the impact, while any visitors in the entire Caribbean-Gulf-tropical Atlantic corridor will need real sargassum-tracker checks before booking a trip. Protected, west-facing beaches tend to fare better than the trade-wind-exposed east coasts that catch the belt head-on, but with mats’ path dictated by ocean currents and wind patterns, it’s a fluid situation. And one that is going away anytime soon.
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