Oh man, the seaweed has been a very serious issue here in the Caribbean... Right now here in Playa del Carmen, for example, you cannot even access the sea for all those piles of rotting seaweed on the beach. I feel so sorry for all those unsuspecting tourists coming here :( From what I heard and read though, the two main causes of this phenomenon is higher sea temperature and water pollution so basically, it is just angry nature striking back at us...