American swimmer Diana Nyad jumped in the sea at Havana Saturday to make her fifth attampt to swim across the Florida Straits, this time in an effort expected to take 80 hours without an anti-shark cage and with better protection against jellyfish.

Nyad, 64, set out Saturday on her latest adventure from the Ernest Hemingway International Nautical Club in the Cuban capital at 9:00 a.m. accompanied by a support team of 39 professionals including divers, doctors, mariners and other assistants.

The first time Nyad tried to swim across the 103 miles (166 kilometers) that separate the coasts of Cuba from Florida was in 1978, when she was protected against sharks but failed to achieve her goal due to adverse weather conditions.

She made two further attempts in 2011, but had to call both of them off due to an asthma attack, box jellyfish stings and storms after swimming for several hours without protection.

In August last year the American returned to Cuba for the same purpose, but when she had completed 60 miles (100 kilometers) at sea, she was forced to give up once more due to the painful jellyfish stings.

Nyad told a press conference Friday in Havana that for this latest swim, her strategy against box jellyfish includes a vaccine created by specialist Angel Yanagihara of the University of Hawaii to counteract and diminish the severe effects of their stings.

She will also wear a bodysuit made of a special fabric, wear special footwear and gloves, use creams, cover her head, cover her face with a silicon mask and wear a prosthesis to protect her mouth.

She said she will wear the bodysuit only at night, the time when jellyfish are most likely to attack, and that she will drink water and eat every 40 minutes.

Though her support team has suggested that she pursue her adventure elsewhere, in Guam or the Maldives for example, Diana Nyad appears determined to stick with her plan and said she won't give up.

"I admit there's an ego rush," Nyad said. "If I three days from now, four days from now am still somehow bringing the arms up and I see the shore ... I am going to have a feeling that no one yet on this planet has ever had." EFE