PUERTO MORELOS, Mexico (AP) – Swaths of seaweed are blanketing the beaches and coastlines of the Caribbean and Gulf of Mexico, suffocating shorelines and snuffing out marine life while spooking visitors in areas that depend heavily on tourism.

Some 27 million metric tons of self-sustaining sargassum have been recorded in the Atlantic, Caribbean and Gulf of Mexico in July, according to a report released Friday by the University of South Florida's Optical Oceanography Lab.

The prickly seaweed covers miles of coastline, releasing a foul smell as it rots onshore.