Plato never said that it was in the Atlantic, he said that it was "before the Pillars of Hercules" that people assume means beyond the Strait of Gibraltar. However, others think that the Pillars of Hercules refers to another location, possibly closer to Greece.
"Just like Atlantis, Ireland is 300 miles long, 200 miles wide, and widest across the middle. They both have a central plain surrounded by mountains."
Problem is that Ireland would have been larger that Atlantis at the time Atlantis was around. It is the same size now due to erosion of the coastline.