Vincent H. Gaddis wrote a fascinating article, "Vanishing Islands" (plus a sidebar or two) for Strange Magazine, issue 16, 1995. I'll have to dig that out and type up a particular quote. It concerns a small group of islands which were discovered by a Spanish ship sailing due west from Panama. An American captain out of SF learned of the islands from an ecclesiastic (yeah, seems farfetched I guess), and decided to visit the islands. He got to the right area, but didn't find them, only some plant matter, as if from a newly submerged or otherwise lost island. S'cool.