Just catching up. . .the placement of Atlantis is based on Plato saying that it was beyond the Pillars of Hercules, usually interpreted to mean beyond Gibraltar. However, there was another set of ancient “pillars” in the Aegean Sea, not far from Thera, also known as the Pillars of Hercules, so Atlantis could very well be Thera.
I'd read that as well, in the 1970s. That second set of pillars is a modern invention. And Plato's description continues, making it quite clear of the location. Further, he gives its size, gives an age -- the only way to move Plato's Atlantis is to throw out his entire tale, which is the only source of the legend.