While scanning through the sci.archaeology newsgroup (see Enigma #2 or the various links pages on the site for a listing of newsgroups related to the mysterious and unexplained) I came across an announcement of a new hypothesis for Atlantis from a Russian by the name of Viatcheslav Koudriavtsev. He was offering to send his hypothesis to any interested party if they requested it by e-mail at:
explor@glas.apc.org
The basis of his hypothesis is that Atlantis did exist, much as Plato described. However, the location was off slightly. Atlantis was not located in the middle of the Atlantic, but rather on what is now referred to as the Celtic Shelf.
The Celtic Shelf is the continental shelf surrounding much of England. This area, currently underwater, was actually above water during the last ice age, over 10,000 years ago.
If you would like his entire piece, write to the address above. It's about 43 KB and goes through quite a bit of background and analysis of the major Atlantean theories.