A 26-year-old woman from Sweden was medically evacuated by the crew of Coast Guard Station Key West on Wednesday night after being stung by a jellyfish.
The woman, whose full name was not released, was reportedly experiencing nausea and paralysis.
She suffered the sting while swimming south of Key West while with the chartered vessel Sebago Cubed, according to the Coast Guard.
The woman was brought to shore, where awaiting emergency medical services took her to the Lower Keys Medical Center. Her condition was not immediately known.
A woman reached at the office of Sebago Cubed said the company would not comment.
The Sebago Cubed offers six-hour power adventures and a 3½-hour Combo Sunset Snorkel Reef, according to its website. It can carry up to 65 passengers.
The sting comes just two days after Diana Nyad completed her 110-mile swim from Cuba to Key West without getting stung by a jellyfish. Two of her previous attempts were thwarted due to multiple jellyfish stings. Australian swimmer Chloe McCardell also had to stop her attempt earlier this year due to stings by the sea creatures.
Nyad wore a protective jellyfish suit at night, when jellyfish are more prevalent. She also lathered a specially created anti-jellyfish cream on her face, feet and hands and on one night wore a silicon mask to prevent the creatures from stinging her.
Jellyfish stings are relatively common for people swimming, wading or diving in sea waters. The long tentacles that trail from their bodies can discharge thousands of microscopic barbed stingers that release venom into a persons skin, according to information published by the Mayo Clinic.
Jellyfish stings can vary greatly in severity, most often causing immediate pain and red, irritated marks on the skin. But the stings can cause whole-body (systemic) illness and, in rare cases, can be life-threatening.