A record amount of sargassum piled up across the Caribbean and nearby areas in May, and more is expected this month, according to a new report. The brown prickly algae is suffocating shorelines from Puerto Rico to Guyana and beyond,

A record bloom of sargassum in places like Puerto Rico and Mexico is impacting beachgoers with its strong smell and can cause skin irritation for swimmers. But as NBC News’ Chase Cain explains, the harm it causes to the environment goes beyond just a bad scent.