Diana Nyad has become the first person to swim from Cuba to Florida without the help of a shark cage.

Chloe McCardel will battle exposure, swift sea currents, stinging jellyfish, sharp-toothed sharks and her own physical limits when she attempts a record swim today from Cuba to Florida.

Endurance athlete Diana Nyad forged ahead through the Straits of Florida with renewed vigour in pursuit of a record 103-mile unassisted swim in open waters without the aid of a shark cage.

American Diana Nyad endured several jellyfish stings as the 62-year-old endurance athlete sought to become the first person to swim unaided from Cuba to Florida without a wetsuit or a shark cage.

A 49-year-old grandmother and veteran endurance swimmer had to give up on her quest yesterday to become the first woman to swim unaided from Cuba to the Florida Keys, unable to close the gap on the last 26 miles of a more than 100-mile ocean odyssey.