By Jeff Franks
HAVANA (Reuters) - With a shout of "courage," veteran long-distance swimmer Diana Nyad dove into the Florida Straits on Saturday and began stroking her way north in her fourth and likely final attempt to make the 103-mile swim from Cuba to the United States.
The 62-year-old American, who will be accompanied by five boats and 50 crewmembers, plied through the blue waters that three times before have bested her with wind, waves and jellyfish, not to mention the threat of sharks.
She had planned to begin the swim on Sunday morning, but weather forecasts called for rising winds later in the 60-hour trip so she took off a day ahead of schedule, hoping for a tranquil sea throughout.
Looking out over the slightly choppy waters at Havana's Marina Hemingway, she said conditions could have been better, but she was ready to go for it.
"This isn't perfect. You can see little whitecaps, but I feel strong in the beginning so why not get a few hours out?" she told reporters.
"I'm really excited. I respect this. I know how difficult it is. There's a reason no one's ever done it, but I'm prepared," she said. "I'm may suffer some, but I'm prepared for that, too."
She also was going across the powerful Gulf Stream, which was flowing due east through the straits instead of a more northerly course that would nudge her toward the Florida Keys.
She hopes to land somewhere in the Keys early on Tuesday, a day ahead of her 63rd birthday on Wednesday.
If she makes it, she will own the world record for the longest "unassisted open ocean swim," which means without a shark cage. Instead of a cage, equipment emitting a mild electric current in the water will keep sharks at bay.
Nyad said she hopes her swim will inspire people her age to continue pursuing their dreams.
"Instead of staying on the couch for a lifetime and letting this precious time go by, why not be bold, be fiercely bold and go out and chase your dreams? " said Nyad, who left competitive swimming 30 years ago and has since worked in television and radio and been a motivational speaker.
She also hoped the swim would help U.S-Cuba relations, which have been sour since the Caribbean island's 1959 revolution.
"My desire is to show the connection between this beautiful country and our beautiful country," Nyad said.
The swim between the two ideological foes has only been completed once, that by Australian Susan Maroney, in May 1997. She was 22 and used a shark cage.
Nyad has tried to make the swim three times, including twice last year, but never got much more than halfway before she had to give up.
Battering waves and winds scuttled her first try in 1978, when she was at the peak of her swimming career. Three years before that she had swum around Manhattan in under eight hours and in 1979, she swam 102.5 miles from Bimini to Florida.
In the middle of an existential crisis about hitting her 60s, she decided to give the Cuba-U.S. swim another go last year, but asthma brought on by jellyfish stings stopped her after 41 hours.
She tried again a month later, but paralyzing stings from what is known as the box jellyfish forced her to give up.
This time she will wear a specially made full-body suit to protect against it, which is one of the reasons she thinks this swim will succeed.
"We need luck, but we do feel we have solved all the problems and know how to address them to get across," she said.
"This has to be it, it just has to be," she said, when asked if this would be her last attempt.
Nyad's swim follows that of Penny Palfrey, a 49-year-old grandmother from Australia, who tried the Cuba-Florida crossing in late June and swam 93 miles before the powerful Gulf Stream forced her to stop.
Palfrey holds the record for the longest unassisted swim, 67.5 miles in the Cayman Islands last summer.
Nyad admitted that while she wished Palfrey well, she was not pulling for her to complete the swim that she has sought for so long.
"It is not my ocean, but it is my dream," she said. "How can I lie? I'm glad that I still have the chance to be first."
(Editing by Cynthia Osterman)