Aha! Enter my theory: The Gulf Of Mexico was blocked off (from the world's oceans) through Florida, Cuba and the Yucatan during the Ice Age. Over thousands of years, the Gulf partially dried out and eventually created a stable but reduced water level in the Gulf. The builders of this 'city' built on the shoreline of the 'reduced water level Gulf.'
When the Ice Age began to end and the world's oceans began to rise, the 'dam' broke and re-flooded the Gulf, submerging these structures. (just like the flood that broke through at the Bosporus and flooded the Black Sea, "Noah's Flood.")
Some are saying that The Bimini Road is associated with the civilization that built the underwater 'city' and was all part of a massive complex in that region. (Throw in a few earthquakes, some volcanic activity and maybe even a meteorite.)
I'm of the opinion that there is more to ancient histroy than we know.
The Cactus Hill site and other sites suggest humans came to the Americas earlier than previously thought.
The sea level was still very low in 12,000.
So any human-built structures at then-sea-level would have to be at least 100 feet down.
With much of Eastern Carribean being shallow, could that have left places like the Cayman depths cut off from the Atlantic?