A few days ago, beachgoers at New Smyrna Beach in Volusia County were horrified to find a jellyfish outbreak which resulted in 406 reported stings in just 48 hours. Purple flags were placed out there to warn people, but people do tend to ignore such warnings - I've been people surfing during tropical storm warnings, and swimming during Red Tide alerts.
I've seen mainstream media news sources state that it is "unknown" what kind of jellyfish were washing up, but I think that's just journalist-speak for "I'm too lazy to found out." I have it on good authority that the most common of the types of jellyfish washing ashore was Stomolophus meleagris, a.k.a. the Cannonball Jellyfish.