The Number: Nyad swims into record books

Diana Nyad is being celebrated as a hero this week for her amazing record-setting swim.

The 64-year-old woman spent almost 53 hours swimming 110 miles from Cuba to Florida. It was the longest distance swim in history, and she did it without a shark cage. During the trek she also had to deal with "currents, shipping lanes, reefs and swarms of jellyfish" – any one of which could have derailed her attempt.

Which to brings us to tonight's number – 5. This was Diana's fifth attempt at the marathon swim. For the past three years, she has tried and failed to accomplish this feat repeatedly, yet has never given up. She was forced to stop because of thunderstorms, asthma attacks and jellyfish repeatedly stinging her.

Each attempt required hundreds of thousands of dollars and the help of dozens of people. It's really more of an expedition than a swim. Fortunately, Diana is an amazingly tough woman.

In fact, the sport is largely dominated by amazingly tough women. The person who held the record before Diana is a woman – Penny Palfrey. And unlike other sports, many of the all-time records in long-distance open-water swimming are held by women.