The sedimentary record of most Florida Bay islands is an asymmetric cycle consisting of a transgressive sequence followed by a regressive sequence, both formed during a continuous Holocene rise in sea level. The principal sedimentary environments of Florida Bay and the south Florida mainland are represented in the cycle by an upward succession of (1) freshwater pond, (2) coastal mangrove swamp, (3) shallow bay (“lake”), (4) mud bank, and (5) island. Some parts of the cycle may be missing, but the sequence is always the same. Supratidal carbonate sedimentation on islands may develop from coastal mangrove swamps or by mangrove colonization of mud banks. Islands have developed from mud banks at many different times during the rise of sea level into Florida Bay, indicating that mud banks must have existed throughout most of the history of the bay. Present trends of island formation and growth suggest that Florida Bay will evolve into a coastal carbonate plain with inland mangrove swamps and freshwater ponds, very similar to the present southwest Florida mainland.