Havana, Cuba (CNN) -- Slathered in a thick coat of sunscreen, Australian endurance swimmer Chloe McCardel leapt into the waters off Havana on Wednesday in her bid to swim the Straits of Florida.
If successful, McCardel will set a world record for the longest unassisted swim. She said she expected her marathon swim through shark- and jelly fish-infested waters to take 60 hours.
"I think it will all work out well," McCardel, 28, said Wednesday minutes before diving into the calm waters off the Cuban capital. "It will be tough though; it's not going to be an easy ride. But we will get through it as a team."
The attempt has cost around $150,000 to finance, McCardel said earlier. She said she hopes to raise money for cancer research and try to improve U.S.-Cuba relations.
Each stroke the Australian swimmer takes will be monitored by teammates in two boats escorting her and by scientists at three universities in the United States.
But other than liquid meals handed to her in a bottle every half-hour by a kayacker paddling near her, McCardel said she would not receive help during the long-distance swim and not use any swim aids such as flippers or a wet suit.
In 1997, fellow Australian Susie Maroney swam the straits from inside a shark cage.
Since then, several high-profile attempts to cross the Florida Straits without a shark cage have been attempted. All have failed.
McCardel said she would use "a shark shield" device that emits an electromagnetic pulse to keep away hungry predators.
She also possibly will be exposed to jellyfish stings as she is forgoing a full-body suit that would offer some protection.
Such a suit would also offer her warmth during the marathon swim. But McCardel, who has completed six solo crossings of the English Channel, said she doesn't think water temperature will be a major factor.
"I have been sweating swimming here," she said.
McCardel said she thinks her greatest advantage will be a team of scientists who have studied the lessons of previous failed attempts and will be in constant touch with people on the boats accompanying her, supplying weather and ocean current updates.
"We can turn a negative situation into a positive one," said Bob Olin, McCardel's boat captain who has participated in four previous attempts by swimmers to cross the Florida Straits. "We can't afford a negative; we can't go backward."
Despite the technology and people assisting her, McCardel will ultimately be alone with her thoughts in the water as she struggles for hour after hour to reach the Florida Keys.
"If I ever get frustrated, I think about something positive to help propel me forward," she said. "I visualize the finish, what it will be like when I walk up on shore."