Estero Bay is a long, shallow estuary and lagoon located on Florida's southwest coast, southeast of Fort Myers Beach. Bordered by a chain of barrier islands including Estero Island, Lovers Key, and Big Hickory Island, it covers approximately 15 square miles. The bay is an inlet of the Gulf of Mexico, formed about 5,000 years ago. It receives freshwater input from several small rivers and creeks, including the Estero and Imperial Rivers, rather than one major river. This creates a productive brackish environment with restricted tidal exchange. The northern half of the bay was designated as Florida's first aquatic preserve in 1966, with the southern half added later, now collectively known as the Estero Bay Preserve State Park. The combination of subtropical climate, lagoon configuration, and extensive vegetation makes it one of the most productive estuarine complexes in the state, supporting a vast array of fish species and providing critical nursery habitat.