A 62-year-old American woman is making her fourth attempt to become the first person to swim from Cuba to the US without the protection of a shark cage. Diana Nyad has already been stung several times by jellyfish but is continuing her 166km (103 mile) journey, team members said. She left the Cuban capital, Havana, on Saturday afternoon and is aiming to reach Florida on Tuesday. She is relying on an electronic shield as a shark deterrent. Nyad, who first attempted to swim in 1978, is hoping to become the first person to set a record crossing of the Florida Straits unaided. The long-distance swimmer was forced to abort her most recent attempt last September after potentially deadly jellyfish stings.

An earlier attempt was meanwhile cut short by shoulder pain and an asthma attack. According to her support team, Nyad was first stung on the neck just five hours into the journey, by the indigenous Olindias formosa jellyfish (aka Flower Hat Jelly) - not the more dangerous box jellyfish that ended her bid last year. “She was treated with topical cream, remained calm and continues to swim,” her support team reported.