Swimming: Naiad in Vaseline

The Strait of Messina, a turbulent, six-mile-wide ribbon of water that separates Sicily from the toe of Italy, has never been a popular place for water sports. It was the home of Scylla and Charybdis, the mythological monsters that wrecked ships and snatched unsuspecting seamen from their decks. And if sailors beware, swimmers positively shun the place. Only the very rash—or the very bold—venture into its treacherous currents.

The water temperature was a frigid 54° one day recently when Mary Margaret Revell, a pretty blonde of 25, stepped into the surf at...