Sargassum seaweed blobs are nothing new, although their scope has increased in recent years.

Scientists have been tracking massive accumulations since 2011, but this year promises to have the largest one yet at over 5,000 miles – twice the width of the continental US.

The blobs usually bob passively in the ocean, carried by the currents until they might dump parts of their fringes along the coastline.

This year’s blob is approaching Florida’s coastline, stretching from the Gulf of Mexico to the shores of Africa.

The blob will push up through the Caribbean and up into the Gulf of Mexico over the summer, with seaweed expected to begin arriving on beaches in Florida around July.

While the blobs are good for some sea life – providing vital habitats for loggerhead sea turtles and as a nursery for commercially vital fish such as mahi mahi, jacks and amberjacks – they can be devastating for coastal communities that rely on tourism as the seaweed piles up 5 or 6 feet deep.

It can also leave behind dead zones in the ocean it passes over, sucking up oxygen in the water.

The sargassum blob will cross the Gulf just in time for the Gulf hurricane to start picking up, and it’s unclear how the two will interact.