Mexican Caribbean beaches coated with thick seaweed.

Javier Rojo Gomez Beach in the Sian Ka&#039;an Biosphere Reserve coated with thick seaweed on July 17, 2015.

Javier Rojo Gomez Beach in the Sian Ka&#039;an Biosphere Reserve coated with thick seaweed on July 17, 2015.

Javier Rojo Gomez Beach in the Sian Ka&#039;an Biosphere Reserve coated with thick seaweed on July 17, 2015.

Javier Rojo Gomez Beach in the Sian Ka&#039;an Biosphere Reserve coated with thick seaweed on July 17, 2015.

Workers clear Sargassum algae at Punta Xcatik
Beach, in a Hotel Resort near Playa del Carmen, on July 18, 2015.

Workers clear Sargassum algae at Punta Xcatik
Beach, in a Hotel Resort near Playa del Carmen, on July 18, 2015.

Workers clear Sargassum algae at Punta Xcatik
Beach, in a Hotel Resort near Playa del Carmen, on July 18, 2015.

Workers clear Sargassum algae at Punta Xcatik
Beach, in a Hotel Resort near Playa del Carmen, on July 18, 2015.