"this island was the way to the other islands; and from these you may pass to the to the opposite continent, which encompasses the true ocean"...
Plato put Atlantis outside the straits of Gibraltar. The opposite continent mentioned is the Americas. While I find it likely that much of the continental shelf was exposed all over the world during the glaciations, and that humans lived there, Atlantis was in the Atlantic, or it was nowhere.
Plato didn't say one word about Gibraltar.