Daunting 100-mile swim: Sharks, jellyfish and more, oh my!

HAVANA, Cuba (CNN) -- All that stands between Chloe McCardel and her dream is 100 miles of shark-infested, treacherous waters.

On Wednesday, McCardel, 28, is expected to leap into the ocean off Havana to begin her bid to be the first person to cross the Florida Straits unassisted.

"It is the hardest swim in the world today," McCardel told reporters at a press conference here Tuesday. "No one's able to do it. This is like the World Cup, if you are into soccer. Like getting a gold medal and world record at the Olympic Games."

McCardel said she has planned on the swim taking 60 hours to complete.

The attempt has cost around $150,000 to finance, McCardel 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 Mulroney 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 will be potentially exposed to jellyfish stings as she is forgoing a full-body suit that would offer some protection from their painful stings.

The full-body 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 backwards."

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."