Mexico City, Mexico - Mexico is deploying specialized navy ships to fight a massive influx of sargassum on the country's Caribbean beaches, authorities said Thursday, as the smelly seaweed threatens the crucial tourism sector.

Some days, more than 9,000 tons of the brownish seaweed are piling onto Mexico's shores, including in the world-renowned resort cities of Cancun and Playa del Carmen, Environmental Secretary Alicia Barcena told reporters.

"This has been a really difficult, atypical year," she said. The amount of sargassum on Mexico's beaches this year is a four-fold jump from last year, and 27 times more than the historic average.

As part of its $115 million response, Mexico has deployed a fleet of specialized anti-sargassum boats, including two open ocean ships and amphibious vehicles, Naval Secretary Raymundo Morales said.

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Over 500 personnel in protective gear have been posted on beaches to clean up the foul-smelling weeds.

The haul is sold to private buyers for various uses, including energy production.

Tourism is a major industry in Mexico, with the state of Quintana Roo – home to Cancun and Playa del Carmen – bringing in more than $18 billion in tourism revenue last year.

Barcena said the "massive arrival" of sargassum is due to irregular ocean currents starting in 2011.

Originating in the Atlantic Ocean's Sargasso Sea, sargassum was pushed by clockwise currents into nutrient-rich waters where it has exploded in growth.