This is what they can look like.
That's the waterfront of the Mexican tourist Mecca, Cancun. Apparently the stench is appalling, bad enough that tourists are canceling reservations.
The picture-perfect beaches and turquoise waters that people expect from the Caribbean are increasingly being fouled by mats of plant matter that attract biting sand fleas and smell like rotten eggs.
Clumps of the brownish seaweed, known as sargassum, have long washed up on Caribbean coastlines, but researchers say the algae has exploded in extent and frequency in recent years.
From the Dominican Republic in the north, to Barbados in the east, and Mexico’s Caribbean resorts to the west, officials are authorising emergency money to clear stinking mounds of seaweed that in some cases have piled up to nearly three metres (10 feet) high on beaches, choked scenic coves and cut off moored boats.
For the last few years Chinese fishermen and beachgoers have faced something similar:
While out here, the Pacific Northwest is living with "The Blob" and an algae bloom stretching from northern California to northern British Columbia.
Inland, Lake Erie's toxic algae bloom has returned. Sorry, Pelee Island.
What these events show is that the way we're living is compatible with actually living. We're not only fertilizing our farm fields, we're also fertilizing the algae in our lakes and oceans. And, where our handiwork erupts, we're creating dead zones that kill off fish species and, left unchecked, create water acidification.
I don't know, isn't it time we tried something else?