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© Jeff Langlois/ZUMAPRESS.comSpinner sharks are seen near the shore Tuesday morning at Midtown Beach.
It's Shark Month in South Florida, and authorities are asking beachgoers to use caution.

Tens of thousands of sharks, heading north to North Carolina after migrating south for the winter, have been spotted by marine biologists in the last week.

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© Jeff Langlois/ZUMAPRESS.comBeachgoers gave the spinner sharks a wide berth and stayed out of the water.
Researchers at Florida Atlantic University have counted 15,000 sharks, most less than 200 yards from shore, according to ABC News. Earlier this week, Midtown Beach in Palm Beach was closed when a school of dangerous spinner sharks were spotted by lifeguards.

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© Jeff Langlois/ZUMAPRESS.comThe spinners were quite a site to see for those on the beach.
The migration happens every year, but usually begins and ends before peak beach season.


"It's the beauty of living in Florida," Laura Salerno of Palm Beach told ABC News. "It's also the danger."

As a precaution, many Florida beaches are displaying double red flags to keep swimmers out of the water.