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.

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.

These vast mats of smelly seaweed may have entered a self-sustaining cycle, effectively feeding their own expansion