5 Eleuthera Island -ThinkstockPhotos-503986350.jpg

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In October 2014, Australian swimmer Chloe McCardel swam 78 miles in 42.5 hours. This is the longest open-water solo, continuous marathon swim in history, according to Associated Press. The 29-year-old had to fight about 15 jellyfish bites, even though she wore a standard suit, and sunstroke to reach the shore. She was readmitted into a hospital because of the stings, some of which got infected.