Atlantis as a composite flood tradition

Do you think Atlantis existed?

Its existence in the familiar form is uncertain; memories of several flooded coastal cities could have combined into the legend.

It is uncertain whether Atlantis existed in the familiar form of the legend. One possibility is that important coastal cities were lost to major floods. Memories of several such places could then have combined into one story. Arthurian legends supply an analogy for that process, without establishing that it happened in this case.