Jack Messenger was one of the unlucky victims.
"Well I was just swimming over here in the water, and I kind of dove backwards to try to dive down and just agony exploded all across my face and before I knew it I couldn't see out of one eye," Messenger told the eastern North Carolina ABC affiliate WCTI.
Messenger said he's been swimming at Emerald Isle for the last 22 years, but this is the first time he's ever been stung by a jellyfish.
Due to the jellyfish danger, the beach flew purple flags Monday to warn beachgoers.
Purple flags are part of the beach warning flag system. They represent "an abundance of potentially hazardous marine life in the vicinity, including Portuguese man-o-war, jellyfish, and other creatures."
"I would never wish (getting stung) upon anyone," Messenger said. "If you see a purple flag up here, stay out of the water."
Emerald Isle lifeguards said they did not notice any jellyfish during their Tuesday rounds, so they have removed the purple flags but still encourage beachgoers to take caution.