Atlantis, as everyone knows, was an ancient island nation of incredible sophistication, advanced technology, and wealth, which sank into the sea in a single cataclysmic moment, and was lost forever. Our earliest account of Atlantis comes from Plato in about 360 BCE, but his descriptions may well have been based on earlier traditions. He claimed they were. Ever since Plato, people have been debating whether or not Atlantis was real (either wholly, or based on real historical elements), but either way it's been enormously influential.
You can look at the original descriptions of the land… Its mountain-girt coast, its concentric rings of land and canals… Its name, meaning "of Atlas" after its king, a son of Poseidon… Its military prowess and threat to Athens…
You can look at attempts to place Atlantis in the real world… from Santorini in the Mediterranean sunk after a volcanic eruption, to Doggerland in the North Sea flooded by a tsunami, to the Azores in the Atlantic never actually sunk at all, to Antarctica, to Andalusia… (That last theory is sketched out in a National Geographic documentary which we enjoyed watching in 2011.)
But while I have a great time looking at these theories and speculating about possible historical connections, in some ways I think all this science (or pseudoscience) is missing the real point. The idea of lost lands and civilizations seems to exist in many cultures and certainly has had an enduring hold on the human imagination, so I think the interesting question is Why are we so fascinated by this? What do these stories provide for us?
The answer changes over time, as is clear by the way the story of Atlantis changes over time. For Plato, Atlantis represented the antithesis of Athens. Athens was the perfect society, and Atlantis was the military juggernaut that threatened it but ultimately was brought down by the only nation noble enough to resist it. (That would be Athens, of course). In the sixteenth century Sir Thomas More coined the word utopia, and the discovery of the New World fueled all sorts of theories connecting Atlantis to the Americas, especially the Mayans. In 1882 there was a great revival in Atlantis mythology, reshaping Atlantis as a utopian center not only of antediluvian culture and technology, but also setting the stage for all sorts of New Age and occult theories about the religion and supernatural powers of Atlantians. So, when we needed to see a powerful enemy destroyed, Atlantis gave us that story. When we needed to explain how "savages" could have built incredible monuments and had a rich culture, Atlantis gave us that explanation. When we needed to cling to a romance of greatness no longer evident and power that might yet be possible, Atlantis gave us that mythology. When we need a cautionary tale about the dangers of hubris or the impermanence of power, Atlantis gives us that warning.
Atlantis or Atlantis-like nations appear in plenty of fantasy, too. From Verne's Twenty Thousand Leagues Under the Sea, to Tolkien's Númenor, from comic books by both DC and Marvel, to video games of multiple types, to an animated movie by Disney, Atlantis remains a popular source of mythology. I'm not immune to the appeal of the ancient advanced civilization long lost. Such a mythology is part of my own book Ruin of Ancient Powers. I'm sure the legend of Atlantis will continue to fascinate and inspire people for a long time to come.
[Pictures: Atlantis, drawing by Géza Maróti, before 1941 (Image from Wikimedia Commons);
Map of Atlantis (north is at the bottom), woodcut from Mundus Subterraneus by Athanasius Kircher, 1665 (Image from OU History of Science Collections).]