Third try at Cuba-US crossing for 62-year-old swimmer

American endurance swimmer Diana Nyad has been stung by jellyfish several times as she seeks to become the first person to swim unaided from Cuba to Florida without a wetsuit or a shark cage.

A member of her support staff posted on Twitter that the 62-year-old was steadily swimming onwards yesterday despite stings to her lips, feet and legs. Her goal is to become the first person to complete the 103-mile crossing of the Florida Strait unaided.

"There are so many jellyfish," one of the tweets said. "Diana is swimming backstroke right now leading with the cap-covered part of her head to minimise contact."

While sharks were among Ms Nyad's concerns, along with potentially treacherous currents and any surprise weather changes, jellyfish that tend to surface at night were a worry, her team said.

Ms Nyad, who is less than a week shy of her 63rd birthday, jumped into the warm waters near Havana on Saturday in her third bid to make the crossing.