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On her fifth attempt, at 64 years old, the legendary long-distance swimmer Diana Nyad became the first person confirmed to swim from Cuba to Florida without the help of a shark cage. She swam for 53 hours from Havana to Key West. “You can't find a stretch of ocean more rife with Mother Nature on steroids — for a swimmer — as you can across the Straits of Florida between Havana and Key West," Nyad says. Some of the dangers include sharks and venomous jellyfish.