I came across a few things which suggest that there were advanced cities in the Caribbean during the last Ice age, which were drowned by rising sea waters. At least two possible sites have been found, one off the western coast of Cuba, and another one in an undisclosed location near the Yucatan Peninsula.
The Cuban one, if it were really man-made would be a real mystery because it is 600 to 750 metres underwater. Far more than could be accounted for by simple sea level rises. Geologists reckon it would have taken at least 50,000 years to sink to that depth. That could potentially re-write the history books on Human civilisation. Strangely though. It was discovered about a decade ago, and little has been heard of it since.
The other one is at a much shallower depth, and is of possible Mayan origin.
I thought this was interesting.