As a longtime Florida dry caver, I can tell you that Florida speleothems are associated with certain limestone layers (regional). With that said, I've heard of underwater speleothems in Citrus and Hernando County. These two counties are home to some of the deepest underwater caves in the world and also are the highest cave areas in peninsular Florida (and home to Florida's deepest dry caves at -95ft and -93ft). The dry caves in the area have lots of formations. I believe that I've heard of formations in Warm Mineral Springs in Sarasota County too. The Tampa Bay is home to the Tampa Bay Geode, which are rarely found out in the bay.
Later,
Dan