How dangerous is it to swim from Cuba to Florida without a protective shark cage?

At Slate, shark scientist and blogger David Shiffman breaks down the risks that swimmer Diana Nyad was really taking this week when she swam from Cuba to Florida without a shark cage. The mere phrase "without a shark cage" makes this sound like a huge risk, Shiffman writes. But the historic swim, itself, is the real achievement. The sharks weren't actually that big of a danger. (BONUS: An explanation of how, exactly, one is supposed to swim long distances inside a shark cage, to begin with.) Read the rest