Seaweed problem in Caribbean: Beaches face unprecedented overgrowth due to climate change, pollution

TULUM, Mexico -- With many trying to enjoy the last bit of summer vacations, an unprecedented overgrowth of seaweed is consuming some beaches.

"Totally impossible to swim," one beachgoer said. "This is the worst piece of garbage water I have ever seen."

In place of the iconic aquamarine water, a brown, stinky seaweed has consumed beaches across the Caribbean, Mexico and even Florida, "Good Morning America" reported.

"We saw a lot of seaweed, more than I've ever seen in the ocean before," another beachgoer added. "It stunk, it got in the way, it kind of affected my whole day."

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Since 2011, floating brown algae called sargassum has been getting progressively worse. This year, it's covering white sand beaches in record levels. There are more than 24 million tons of the algae.

When it dies on the shore, it can be toxic to people, animals and the economy. Scientists have said that climate change and shifting weather patterns likely have something to do with it.

Caribbean water temperatures this year stayed above average all winter. It was the third warmest on record.

"Although we don't have a clear idea, most of the evidence points to warmer sea surface temperatures, so climate change, global warming. And a lot of nutrients don't leave the water," one person said.

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It's not just unsightly and stinky, but it can actually impact sea turtles. Little hatchlings have a hard time climbing over the seaweed. It can shade coral, which is not good, and even throw off the pH of the ocean, which can kill fish.

"One of the major problems is on St. Croix, the intake for the water," said Dr. Paul Jobsis, director at the Center for Marine and Environmental Studies at the University of the Virgin Islands. "We have a desalination plant there. The intake for that is being clogged up by the sargassum. Otherwise, it's just a stinking mess on the beaches."

Cleaning up these beaches could mean big money.

For the U.S Virgin Islands, tourism makes up half of the GDP, so they need to get rid of the seaweed.

Unfortunately, a lot of the big resorts face east, and that is where the sargassum piles up.

Now, they spend thousands a month trying to pick it up, but also have to figure out what to do with it next.