Tourism is an important part of the Mexican economy. And most tourists want to spend time on the nation’s white sand beaches. But recently there has been a problem: seaweed. And a lot of it. Like other countries along the Caribbean Sea, Mexico has been dealing with large amounts of sargassum seaweed on its shores. Now the Mexican government is taking action. Their idea: build barriers on the ocean bottom to keep seaweed from beaches where tourists swim and sun.