I swim 2-3 times per week and usually about 1 to 1.5 miles per. For the average casual and non regular swimmer, they could not do this distance let alone 9 miles.

I am highly skeptical of this person's claim. He may of been in the drink for 10 hours but even with a strong inward current, I don't see it. I am not alone in this thinking. Both the Washington Post and Newsweek are questioning this man's claim. Conveniently, he is not talking about his 9 mile experience...
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Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.

John Lubbock