HAVANA (Reuters) - Under a bright, tropical sun, Australian Chloe McCardel jumped into a calm, crystal-clear sea on Wednesday and began her quest to become the first person to make the 103 mile swim from Cuba to the United States without a shark cage.
If all goes well, she hopes to swim through the Straits of Florida in about 60 hours and reach Key West on Friday night.
McCardel will use a team of scientists in the United States to help guide her through the Gulf Stream, the powerful and unpredictable current that has stymied many previous attempts.
Only one person, Australian Susie Maroney in 1997, has completed the Cuba-U.S. swim, but she used a shark cage, which helps cut through the water.
Wearing a black bathing suit and rubber cap, McCardel, 28, and husband Paul McQueeney lathered her body with a whitish goop to protect against the sun and chafing.
"I'm really excited, I'm trying to stay calm and relaxed and just think about the finish," said the blonde, muscled swimmer whose past accomplishments include two back-and-forth crossings of the English Channel.
"It'll be tough, though. It's not going to be an easy ride, but we'll get through it as a team," she told reporters as she prepared to jump into the straits from a promontory at Havana's Hemingway Marina, the traditional starting point of Cuba-U.S. swims.
McCardel said she is making the swim to encourage donations for cancer research, which can be made on her website www.chloemccardel.com, and to encourage better U.S.-Cuba relations, which have been sour since the Caribbean island's 1959 revolution.
McCardel will face the dangers of sharks, stinging jellyfish and unpredictable weather as she heads north.
She'll be surrounded underwater by an electromagnetic field from a device held in the water that wards off sharks.
Her swim has been timed with the season and moon phase to minimize the presence of the venomous box jellyfish, which have plagued previous swimmers, including American Diana Nyad who was stung repeatedly in August on her fourth failed attempt at the crossing.
Even though the forecast calls for calm seas and light winds, conditions can change quickly in the straits, brewing up wave-churning squalls that wreak havoc with long swims.
The scientific team, part of a small army of 50 people assisting McCardel, is a new twist to the swim, which is considered the Holy Grail of marathon swimming because of the dangers and the distance. McCardel said it is 50 percent farther than the current record swim.
McCardel told reporters on Tuesday that the scientists are all experts on the Gulf Stream, which changes constantly as it courses west to east through the straits, and will use real time data on its currents to create computer models forecasting what lies ahead.
Last summer, British-born Australian Penny Palfrey got tantalizingly close to the Florida Keys but couldn't finish when she swam into a Gulf Stream eddy that pushed her in the wrong direction.
In theory, that kind of setback can be avoided because the crew of McCardel's accompanying boat, the Sunluver, will be warned and can lead her around adverse conditions.
Under marathon swimming rules, McCardel cannot touch the boat or hang on to anything while she makes the crossing.
She'll pause briefly every 30 minutes to gulp down a nutrient-fortified liquid meal from a bottle.
As the swim goes on, she'll have to battle through fatigue from the extreme physical exertion of her swim and a lack of sleep.
But no worries, just before jumping into the sea she was sure enough of her success to invite the commodore of the marina to a party in Key West on Friday night.
"(I'm) as confident as I can be ... I think it's all going to work out well," she said.
Editing by Tom Brown and Kenneth Barry