Sweetwater is a city in Monroe and McMinn counties in the U.S. state of Tennessee, and the most populous city in Monroe County. As of the 2020 census, its population was 6,312. Sweetwater is the home of the Craighead Caverns which contains the Lost Sea, the United States' largest underground lake. In 2022, TravelMag named Sweetwater one of Tennessee's Ten Most Charming Cities.