We’ve already determined that The Tempest was all Shakespeare’s work, the writing of it–and the last one he did write solo. But what about where he pilfered the story? I mean, the Bard was also the Thief of Avon, as we’ve seen many, many times before.
So where’d he get this story?
Interestingly enough, from his own head.
There is no source for the story, a la Holinshed for the histories, or Plutarch for the Roman plays, or any number of other plays and novels (including those from Ovid and Boccaccio).
That’s not to say he didn’t take some things from some(other)ones.
At this point in history, reports from the New World (or at least parts westward [ho!]) were all the rage, and this could have influenced his decision to write about such a deserted island. Of course, in 1610, there were two items published that involved a shipwreck in the Bermudas (a letter from William Strachey and a journal by Sylvester Jourdain–A Discovery of the Bermudas); these, too, may have influenced the work.
If those explain the island and the wreck, then Gonzalo’s Act Two description of his Utopia (as well as the depiction of the “savage” Caliban) may have been influenced by the translation of Michel de Montaigne’s essay “Of Cannibals,” which had been translated into English from the French by John Florio nearly a decade earlier.
But, narratively speaking, The Tempest is an anomaly in Shakespeare’s Canon: it looks to be all his.