South Florida beaches faced a sargassum assault this summer that some scientists believe is part of the largest spread of the nomadic marine weed on record, and one that could continue through September.

Sargassum, a type of marine algae, is washing up en masse on Caribbean beaches, closing them down to the public. The same sargassum is here in Miami, lining Miami beaches.

Heavy mats of seaweed are washing up on South Florida beaches, creating thick barriers to the ocean.