By Maria Pedone
December 03, 2013

Aside from Disney World, I wouldn't normally call a destination magical—but Puerto Rico’s bioluminescent Grand Lagoon comes pretty close. Unfortunately, the popular Fajardo tourist destination has gone strangely dark. Visitors come to swim or kayak through the waters to witness a trail of sparkling green light appear. The glow is caused when dinoflagettlates (microscopic plankton) are disturbed, giving off light they’ve collected during the day. But since November 11, tour operators have been forced to cancel excursions and reimburse disappointed guests.

Scientists and the Department of Natural Resources Secretary Carmen Guerrero have been scouring the bay for hints as to why the neon streaks are no longer appearing, with recent storms and construction allegedly to blame. Ironically, the runoff from a nearby water and sewer plant designed to protect the lagoon may actually be harming the delicate plankton that draw so many tourists. We hope for a bright return of the lagoon's natural phenomena, whose waters also went black back in 2003.

Maria Pedone is on the digital team at Travel + Leisure. Follow her on Twitter at @mariapedestrian.