Seaweed composing the Great Atlantic Sargassum Belt hit near-record levels in June 2026, with the Caribbean Sea and Gulf of America both reaching all-time highs.

Seaweed composing the Great Atlantic Sargassum Belt hit near-record levels in June 2026, with the Caribbean Sea and Gulf of America both reaching all-time highs.

Sargassum, a smelly, brown seaweed that can cause respiratory irritation and other health problems, hit record levels in the Caribbean and the Gulf of Mexico last month.