If you search for the hashtag Zante or Zakynthos on Instagram, almost half of the images of this Greek island are of a sandy bay dominated by the wreckage of an old ship. Navagio Beach and its 43-year-old shipwreck are one of the island’s most visited and photographed attractions, with tour companies offering dedicated excursions. Recent posts on Instagram, however, show just how much the vessel has deteriorated over the course of the last decade. Now, the state of the boat has come to the attention of authorities over fears it might be completely washed away – along with it a large chunk of t…