After reading an article on the Blue Holes of the Bahamas, I became fascinated with these underwater caverns. They were formed during a sea level recession that uncovered much of the Bahamian carbonate platform. Once exposed to the atmosphere, the limestone began to weather and erode, forming caves. When sea level rose, the cave systems were submerged. Only within the past century were these caves explored and documented.
The following is a link to the the article.