U.S. swimmer Diana Nyad begins her challenge of swimming 103 miles between Havana, Cuba and Florida, in a period of three days, without a cage to protect her from sharks, Aug. 7. Nyad, 61, began accompanied by a team of 40 people who will escort her, divided in three vessels in a journey that will last about 60 hours. During the 60 or so hours, from Cuba to Florida, she won't touch land or even a boat. Every hour and a half, she'll stop for some water, an electrolyte drink and maybe a banana with peanut butter. At 29, Nyad set the record for the longest ocean swim at 163 kilometres. That record still stands.

U.S. swimmer Diana Nyad swims on her way to Florida from Havana, while flanked by two assistants in kayaks with an assistance boat in front Aug. 7. The 61-year-old plunged into the Straits of Florida at dusk on Sunday to begin what she hopes will be a world record 103-mile swim from Cuba to Florida. The same swim was completed successfully by Australian Susan Maroney in May 1997. But Nyad's claim to a world record will be that unlike Maroney, she is doing it without a shark cage in the strait's warm, shark-infested waters. Nyad will be protected by a surrounding electrical field and by divers who will watch for sharks and drive them away if they get too close.

U.S. swimmer Diana Nyad begins her attempt to swim to Florida from Havana Aug. 7.