Sargassum is a free-floating brown seaweed that has, since the mid-2010s, periodically washed up in large quantities across parts of the Caribbean coast, including sections of Cancún and the Riviera Maya. It's a real, visible factor in trip planning — worth understanding rather than either panicking about or ignoring.
Why it happens
Large sargassum mats form out in the Atlantic and drift with currents; the amount reaching any given coastline varies by year and season, tied to ocean conditions researchers are still refining models for.
Seasonality
Historically the heaviest arrivals have clustered from around April through August, tapering off outside that window — but there's real year-to-year variation, and some years break that pattern entirely. Treat any specific seasonal claim, including this one, as a general tendency rather than a guarantee.
It's not uniform across Cancún
Beaches facing the open Caribbean (the Hotel Zone's southern/eastern-facing stretches) tend to catch more than beaches facing the calmer Bahía de Mujeres to the north. Hotels also vary a lot in how actively they clean their stretch of beach each morning.
What to do about it
Ask your hotel directly and recently — not from an old review — about current beach conditions. Many resorts post daily photos or updates on their own social channels during heavy seasons. If beach quality is a dealbreaker, consider the calmer north-facing Hotel Zone beaches or a pool-focused stay during the heaviest months.
This page is a general explainer, not a live feed — check hotel-specific updates or official Quintana Roo tourism channels for real-time conditions before you travel.