What Is Sargassum and Why Is 2026 a Record Year?

Published 2026-05-20

What is sargassum?

Sargassum is a brown, free-floating seaweed found throughout the Atlantic Ocean. In small amounts it's a healthy part of the ocean ecosystem, providing habitat for fish, turtles, and crabs. The problem begins when it arrives on beaches in massive quantities. It smells, stings, and can close off swimming areas for weeks at a time.

Why 2026 is different

Early satellite data from NOAA and Copernicus Marine shows that the Great Atlantic Sargassum Belt, a mass of seaweed stretching from West Africa to the Gulf of Mexico, reached record size in early 2026. Unusually warm sea surface temperatures in the tropical Atlantic and elevated nutrient levels from river runoff have created near-perfect conditions for growth.

Which beaches are most affected?

Beaches facing east and southeast along the Caribbean arc tend to receive the most sargassum. The Mexican Riviera Maya, parts of Barbados, and the eastern coasts of the Dominican Republic have historically been the hardest hit. Sheltered bays, west-facing beaches, and locations inside reef systems tend to fare significantly better.

What can you do?

Check current conditions before you book or travel. SeaweedFree tracks daily satellite data and visitor reports so you can find cleaner beaches nearby, or know what to expect before you arrive.