Courtesy of WOWSA, Huntington Beach, California.

According to the University of Florida’s International Shark Attack File, a swimmer’s chances of being attacked by a shark in the U.S. are 1 in 11.5 million.

We looked for the data supporting this probability assumption.

Various organizations report that between 75-100 million people go to the beach each year in the U.S. Assume an average of 40% of beach-goers actually swim, this means between 30-40 million people get in the water. Assume an average number of visits per individual is two per year, that means there are 60-80 million chances of a human along America’s coast to be attacked.

But assume that most of these individuals (over 80%) only enter the ocean at relatively shallow depths where most sharks never venture (i.e., within the surf break).

This may mean that there are realistically a 1-in-11.5 million chances of being attacked.

What does this probability in real terms mean? According to National Geographic News, the United States averages 16 shark attacks each year and slightly less than one shark-attack fatality every two years.

Photo shows flesh wounds of Steven Robles after a shark encounter along Manhattan Beach in Southern California.

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