Some people belive that this was naturally made. But other people belive that this could be a part of the lost city os Atlantis - first spoken of by Plato.
An argument strongly supported this second group would be a porphecy made in 1938 by Edgar Cayce, that say "A portion of the temples can still be discover under the slime os ages and sea water near Bimini... Expect it in '68 or '69 - Not so far way"