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.

Lee County is located in southwestern Florida, United States, on the Gulf Coast. As of the 2020 census, its population was 760,822. In 2022, the population was 822,453, making it the eighth-most populous county in the state. The county seat is Fort Myers, with a population of 86,395 as of the 2020 census, and the largest city is Cape Coral, with an estimated 2020 population of 194,016.