- Siegel
- Sigsbee
- Silica
- Silver Creek
- Silver Creek
- Silver Rapids
- Silverdale
- Silverwood
- Simar
- Simley Island
- Simpson
- Sioux Pine Island
- Sioux Valley
- Skibo
- Skime
- Skunk Island
- Skyberg
- Skyline Gardens Mobile Home Park
- Skyline Mobile Park
- Smith Island
- Smith Lake
- Smiths Mill
- Smithville
- Smolich Island
- Smoot Island
- Snake Island
- Snake Island
- Snellman
- Snellman Island
- Snowden