Yes, Key Largo does receive sargassum (brown seaweed), particularly during the late spring and summer months when the "Great Atlantic Sargassum Belt" is at its peak. However, the impact on Key Largo is often different than on the beaches of Miami or Cancun. Because Key Largo is primarily composed of fossilized coral rock rather than vast sandy beaches, the sargassum tends to collect in the shallow mangroves, canals, and around the few man-made beaches like those at John Pennekamp Coral Reef State Park. While it can be unsightly and produce a sulfurous "rotten egg" smell as it decomposes, it is a vital part of the ecosystem, providing habitat for juvenile sea turtles and fish. In 2026, many high-end resorts in Key Largo use "sea curtains" (floating booms) to deflect the seaweed away from their swimming areas. If you are visiting for snorkeling or diving, the sargassum usually doesn't affect the deeper offshore reefs, though it can occasionally reduce visibility in the very shallow near-shore "flats" during heavy influxes.