It is often true that legends are based on a physical reality of some kind,  even though they may become greatly confused down through the ages.  The legend of Atlantis is an account written by Plato,  which he learned from a fellow Greek, who had  heard it from Egyptian priests. They claimed that, in terms of history,  the Greeks " were but children." compared to their civilization, which was thousands of years older.

If his description is to be taken literally, then there was no Atlantis.  Plato's account described a war between Atlantis and Greece some 9000 years before his time.  There was no Greece at that time,  just Neolithic tribesman.  However, the Egyptian and Greek numerical systems were both cumbersome and confusing.  If the numbers had all been  misinterpreted by a factor of ten,  then the account may make sense.  There had been a war between Greece ( Myceans ) and the Minoan civilization on Crete about 900 years before.  There had been a dark age in Greece just following the Myceans.

The location of Atlantis had been described as being beyond the Pillars of Hercules.  This has often been interpreted as the Straights of Gibraltar, which would put Atlantis somewhere in the Atlantic. Geologists seem to agree there would be no place for a sunken civilization in the Atlantic.  However, there was another geological formation of  the same name,  located just south of Greece. Atlantis was described as being " greater " than Africa and Asia, but the word might also have been translated as "between".

Around 2500 BC,  located just north of Crete, there had been a tremendous volcanic eruption on the island of Thera.  The explosion had blown a crater over ten miles across, virtually destroying the island,  which could have been the capital city described by Plato.  The eruption also buried areas of Crete under layers of volcanic ash and caused huge tsunamis.  To a traveler returning to the area after the eruption,  it might well appear that the Minoan civilization had simply disappeared. Navigation at the time was very primitive,  and they may have assumed they had landed elsewhere.