Estero Island is an island located in Lee County, Florida, on the Gulf coast of Southwest Florida. It is bordered by San Carlos Island to the north and Big Carlos Pass to the south. The Matanzas Pass Bridge is on the northern end of the island and connects Estero Island over Matazanas Pass to San Carlos Island. The Big Carlos Bridge (part of the Bonita Beach Causeway) connects the southern end of the island to Black Island (the northern limit of the city of Bonita Springs).
The island is part of the town of Fort Myers Beach.