Published: Aug 08, 2011 3:47 PM EDT

HAVANA (AP) - Endurance swimmer Diana Nyad stroked through the Florida Straits early Monday, trying to accomplish at 61 years old what she failed to do at 28: swim more than 100 miles from Havana to Key West.
    
If she makes it to the Florida Keys after an estimated 60-hour swim, Nyad would become the first person to traverse the strait without the aid of a shark cage. She's relying instead on technology and divers to fend off the finned predators.
    
Tanned and freckled from long hours training in the open seas of the Caribbean, she expressed confidence before starting off just before sunset Sunday. She said the still air and shimmering water were perfect conditions for her attempt to make a 103-mile swim.
    
Nyad first tried the crossing back in 1978, when she swam inside a steel shark cage for about 42 hours before sea currents hammering her off course put an end to the attempt.

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