Mound Key Archaeological State Park is a Florida State Park, located in Estero Bay, near the mouth of the Estero River. One hundred and thirteen of the island's one hundred and twenty-five acres are managed by the park system. It is a complex of mounds and accumulated shell, fish bone, and pottery middens that rises more than 30 feet above the waters of the bay.

The Estero River is a 6.4-mile-long (10.3 km) waterway in south Lee County, Florida, United States, near the village of Estero. It flows from east to west, emptying into Estero Bay, an inlet of the Gulf of Mexico.