Penny Palfrey, 49, attempts 103 mile swim from Cuba to Florida without a shark cage

British-Australian swimmer Penny Palfrey will today begin an attempt to become the first person to swim across the Florida Straits without a shark cage or swim aids.

AFP says that the 49-year-old mother of three and grandmother of two was due to set off from the Hemingway International Yacht Club in Cuba's capital Havana at dawn. She was expected to arrive at Key West in Florida, across shark-invested waters, three days later.

"She will swim continuously 103 miles or 166 kilometers under standard open-water swimming rules.  That means no wetsuit, no shark cage," her husband, Chris Palfrey, is quoted as saying by CNN. If she succeeds Palfrey would beat the previous record for the longest unassisted swim that she set in 2011 when she swam more than 67 miles from Little Grand Cayman island to Big Grand Cayman island. 

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In 1997, another Australian swimmer Susie Maroney completed a similar swim at the age of 22, but with a shark cage, according to Associated Press.  American Diana Nyad, 62, made two attempts without a cage last year, but they were cut short by asthma attacks and jellyfish stings.

Instead of a shark cage, Palfrey will rely on "sharkshields," explains MSN News, which generate an electrical field in the water and deter sharks.   She will also wear a Lycra bodysuit when Portuguese man o' war stings threaten to pose a problem.

"Every single swim is individual. Each swim comes with its own challenges. This is a really big challenge, the Florida Straits, 103 miles," Palfrey told Reuters ahead of the swim.

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