Describe the 1891 experiment. Is this a valid experiment? Why or why not?

In July 1891, the luxury yacht, Hildegard, set off on an outing in the Atlantic off the New York coast. On board were the architect Stanford White, New York Sun publisher Charles Dana, and close friend Theodore Roosevelt. The owner and captain of the yacht was the wealthy shipping mogul Hermann Oelrichs. One of Oelrichs' goals was to debunk the myth that sharks were man-eaters. He felt certain that their bad publicity stemmed from pure fantasy. He had offered a reward of $500 for proof that any person had ever been attacked by a shark. As the yacht sailed into deep waters, the fins of several sharks were spotted. Oelrichs dived in among them and, amazingly, he swam and splashed among them unharmed, chasing the large sharks away. He felt he had made his point. This is not a valid experiment, because it only took place one time and it is not known what types of sharks with which the man swam.