Atlantis was one of the fictional societies Plato described to illustrate his ideas. Before Plato, there was NO reference to Atlantis or an Atlantis like society. All such references since stemmed from Plato's obvious philosophical construct.
The hunt for Atlantis is, quite literally, as comical and laughable as people trying to find the "Real" Hogworts, Utopia or Mordor 5,000 years from now.
There was never an Atlantis, it was obvious from Plato's work he never expected anyone to think it was real. Despite this brain dead morons have spent entire lifetimes trying to manufacture "proof" of a fictional society created to illustrate philosophical ideals. While I first learned this startling truth in a college philosophy course, the Wikipedia article on Atlantis is a good starting point for those new to the topic.
It was a common convention in Plato's time to create a fictional society or city to illustrate a philosophical point or argument. No one really considered "Atlantis" anything more than a philosophical construct until the 19th century or so. Around that time some of the noteworthy flakes started merging assorted "lost world" myths in a desperate attempt to give them some credence. The general idea seemed to be if they took enough unrelated, unsupported legends and combined them, they could create something with a sheen of plausibility.
The fact that people are still discussing the possibility of an obviously fictional island is proof their patchwork creativity worked.