Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Sniffea Cemetery | Cemetery | 259 | Dubuque | 42 29 20 N | 090 46 40 W |
| Snipe Creek | Stream | | Jasper | 41 48 27 N | 093 02 44 W |
| Snively Access | Locale | 178 | Louisa | 41 11 15 N | 091 06 18 W |
| Snort Creek | Stream | | Appanoose | 40 46 53 N | 092 49 13 W |
| Snow Hill | Locale | 329 | Page | 40 41 25 N | 095 13 46 W |
| Snow Hill Cemetery | Cemetery | 331 | Page | 40 41 25 N | 095 14 22 W |
| Sny Magill (historical) | Locale | 187 | Clayton | 42 56 15 N | 091 10 20 W |
| Sny Magill Creek | Stream | | Clayton | 42 56 10 N | 091 10 00 W |
| Sny Magill North Cedar Creek Wildlife Management Area | Park | 247 | Clayton | 42 57 30 N | 091 13 00 W |
| Snyder | Locale | 307 | Dallas | 41 49 10 N | 093 51 50 W |
| Snyder Access | Locale | 276 | Dallas | 41 44 35 N | 094 03 21 W |
| Snyder Bend Park | Park | 328 | Woodbury | 42 17 10 N | 096 20 21 W |
| Snyder Branch | Stream | | Appanoose | 40 47 49 N | 092 52 15 W |
| Snyder Bridge | Locale | 254 | Polk | 41 48 14 N | 093 47 42 W |
| Snyder Cemetery | Cemetery | 199 | Van Buren | 40 42 30 N | 091 44 51 W |
| Snyder Creek | Stream | | Johnson | 41 34 47 N | 091 31 38 W |
| Snyder Creek | Stream | | Mahaska | 41 17 17 N | 092 26 30 W |
| Snyder Post Office (historical) | Post Office | 308 | Dallas | 41 48 20 N | 093 50 46 W |
| Snyder School | School | 313 | Clarke | 41 08 51 N | 093 36 58 W |
| Snyder Wildlife Management Area | Park | 467 | Osceola | 43 26 40 N | 095 26 46 W |
| Snyder-Winnebago Bends Area | Park | 324 | Woodbury | 42 15 40 N | 096 19 51 W |
| Snyder's Grove Post Office (historical) | Post Office | 347 | Woodbury | 42 18 00 N | 096 07 06 W |
| Snyders Grove | Locale | 326 | Woodbury | 42 18 01 N | 096 08 03 W |
| Soap Creek | Stream | | Lee | 40 23 11 N | 091 23 36 W |
| Soap Creek | Stream | | Wapello | 40 53 57 N | 092 12 49 W |
| Soap Creek Wildlife Area | Park | 245 | Davis | 40 52 10 N | 092 37 01 W |
| Soaring Eagles Nature Center | Locale | 232 | Clinton | 41 53 43 N | 090 10 30 W |
| Soccer and Intramural Fields | Park | 253 | Linn | 41 55 23 N | 091 25 41 W |
| Social Plains School | School | 301 | Warren | 41 15 47 N | 093 34 36 W |
| Sockum Ridge County Park | Park | 215 | Washington | 41 13 06 N | 091 39 02 W |
| Sockum Ridge Park Trail | Trail | 215 | Washington | 41 13 10 N | 091 39 06 W |
| Soda Bar Post Office (historical) | Post Office | 362 | Palo Alto | 43 00 35 N | 094 38 21 W |
| Sodus Creek | Stream | | Clinton | 41 44 35 N | 090 19 17 W |
| Sodus School (historical) | School | 183 | Clinton | 41 45 23 N | 090 20 09 W |
| Solar Eclipse of 1869 Historical Marker | Park | 206 | Des Moines | 40 48 21 N | 091 06 30 W |
| Soldier | Populated Place | 355 | Monona | 41 59 07 N | 095 46 46 W |
| Soldier (historical) | Locale | 351 | Monona | 41 59 00 N | 095 46 43 W |
| Soldier Bend Wildlife Area | Park | 306 | Harrison | 41 41 45 N | 096 06 21 W |
| Soldier Cemetery | Cemetery | 368 | Monona | 41 57 05 N | 095 46 48 W |
| Soldier Church | Church | 368 | Monona | 41 57 06 N | 095 46 48 W |
| Soldier Community Building | Building | 356 | Monona | 41 59 05 N | 095 46 47 W |
| Soldier Creek | Stream | | Buena Vista | 42 52 57 N | 095 10 38 W |
| Soldier Creek | Stream | | Emmet | 43 25 56 N | 094 37 31 W |
| Soldier Creek | Stream | | Webster | 42 30 21 N | 094 11 58 W |
| Soldier Elevator | Locale | 355 | Monona | 41 58 57 N | 095 46 58 W |
| Soldier Lutheran Church | Church | 361 | Monona | 41 59 18 N | 095 46 55 W |
| Soldier Monument | Park | 368 | Sac | 42 25 19 N | 094 59 16 W |
| Soldier Post Office (historical) | Post Office | 358 | Monona | 41 58 44 N | 095 46 03 W |
| Soldier River | Locale | 307 | Harrison | 41 09 15 N | 096 01 17 W |
| Soldier River | Stream | | Harrison | 41 44 15 N | 096 05 52 W |
| Soldier River Cutoff | Canal | 313 | Harrison | 41 45 10 N | 096 01 43 W |
| Soldier Town Hall | Building | 356 | Monona | 41 59 05 N | 095 46 47 W |
| Soldier Valley | Locale | 321 | Harrison | 41 47 25 N | 095 57 09 W |
| Soldier Valley (historical) | Locale | 317 | Harrison | 41 47 28 N | 095 57 51 W |
| Soldier Valley Cemetery | Cemetery | 338 | Harrison | 41 47 30 N | 095 57 18 W |
| Soldier Valley Post Office (historical) | Post Office | 321 | Harrison | 41 47 25 N | 095 57 09 W |
| Soldier's Home Cemetery | Cemetery | 278 | Marshall | 42 03 21 N | 092 55 53 W |
| Soldiers and Sailors Monument | Park | 244 | Polk | 41 35 23 N | 093 37 11 W |
| Soldiers Field | Park | 281 | Polk | 41 34 03 N | 093 35 01 W |
| Soldiers Monument | Park | 367 | Cass | 41 24 15 N | 095 00 51 W |
| Solferino Creek | Stream | | Lee | 40 31 20 N | 091 23 15 W |
| Solid Rock Baptist Church | Church | 177 | Louisa | 41 11 08 N | 091 11 26 W |
| Solid Rock Christian Church | Church | 197 | Johnson | 41 40 09 N | 091 33 52 W |
| Solid Rock Christian Church | Church | 253 | Polk | 41 40 20 N | 093 42 21 W |
| Solid Rock Church | Church | 399 | Union | 41 04 15 N | 094 21 25 W |
| Solid Rock Church of God | Church | 306 | Appanoose | 40 44 00 N | 092 52 26 W |
| Solid Rock Fellowship | Church | 236 | Keokuk | 41 11 07 N | 091 59 41 W |
| Sollberg | Populated Place | 376 | Wright | 42 44 20 N | 093 38 13 W |
| Solomon | Populated Place | 344 | Mills | 40 54 19 N | 095 26 31 W |
| Solomon (historical) | Locale | 344 | Mills | 40 54 19 N | 095 26 31 W |
| Solomon Post Office (historical) | Post Office | 344 | Mills | 40 54 19 N | 095 26 31 W |
| Solon | Populated Place | 244 | Johnson | 41 48 26 N | 091 29 39 W |
| Solon (historical) | Locale | 242 | Johnson | 41 47 55 N | 091 29 34 W |
| Solon City Hall | Building | 241 | Johnson | 41 48 21 N | 091 29 44 W |
| Solon Family Practice Clinic | Hospital | 232 | Johnson | 41 48 25 N | 091 29 56 W |
| Solon Fire Station | Building | 241 | Johnson | 41 48 21 N | 091 29 44 W |
| Solon Junior Senior High School | School | 241 | Johnson | 41 48 19 N | 091 29 44 W |
| Solon Nursing Care Center | Hospital | 250 | Johnson | 41 48 08 N | 091 29 21 W |
| Solon Post Office | Post Office | 243 | Johnson | 41 48 24 N | 091 29 41 W |
| Solon Public Library | Building | 237 | Johnson | 41 48 32 N | 091 29 44 W |
| Solon United Methodist Church | Church | 241 | Johnson | 41 48 27 N | 091 29 47 W |
| Somar Family on Wright Farm Cemetery | Cemetery | 334 | Mills | 41 02 30 N | 095 42 01 W |
| Somber | Populated Place | 391 | Worth | 43 25 21 N | 093 23 57 W |
| Somber Cemetery | Cemetery | 385 | Worth | 43 24 54 N | 093 24 18 W |
| Somber Church | Church | 387 | Worth | 43 24 56 N | 093 24 15 W |
| Somber Post Office (historical) | Post Office | 391 | Worth | 43 25 21 N | 093 23 57 W |
| Somers | Locale | 353 | Calhoun | 42 22 52 N | 094 25 48 W |
| Somers | Populated Place | 352 | Calhoun | 42 22 42 N | 094 25 48 W |
| Somers City Hall | Building | 352 | Calhoun | 42 22 42 N | 094 25 48 W |
| Somers City Library | Building | 352 | Calhoun | 42 22 42 N | 094 25 48 W |
| Somers Post Office | Post Office | 352 | Calhoun | 42 22 42 N | 094 25 48 W |
| Somida Post Office (historical) | Post Office | 382 | Shelby | 41 39 11 N | 095 19 32 W |
| Sommers Cemetery | Cemetery | 218 | Washington | 41 11 34 N | 091 39 03 W |
| Sonora (historical) | Locale | 276 | Poweshiek | 41 51 38 N | 092 39 34 W |
| Sonora Post Office (historical) | Post Office | 276 | Poweshiek | 41 51 38 N | 092 39 34 W |
| Sons of Jacob Cemetery | Cemetery | 277 | Black Hawk | 42 29 03 N | 092 17 02 W |
| Soo River Access | Locale | 364 | Cherokee | 42 52 35 N | 095 28 01 W |
| Sopers Mill Access Area | Park | 284 | Story | 42 06 16 N | 093 34 32 W |
| Sopers Mill Bridge | Bridge | 279 | Story | 42 06 10 N | 093 34 31 W |
| Sorden Cemetery | Cemetery | 260 | Keokuk | 41 27 27 N | 092 11 27 W |
| Souhrada Forest Wildlife Area | Park | 388 | Howard | 43 29 35 N | 092 13 31 W |
| Sourwine Cemetery | Cemetery | 189 | Des Moines | 40 44 50 N | 091 08 01 W |
| South 80 Field | Airport | 369 | Hancock | 43 11 27 N | 093 46 15 W |
| South Amana | Populated Place | 237 | Iowa | 41 46 34 N | 091 58 03 W |
| South Amana Barn Museum | Building | 235 | Iowa | 41 46 35 N | 091 58 01 W |
| South Amana Pond | Lake | 246 | Iowa | 41 46 14 N | 091 58 56 W |
| South Amana Post Office | Post Office | 235 | Iowa | 41 46 35 N | 091 58 01 W |
| South Augusta | Populated Place | 168 | Lee | 40 45 08 N | 091 16 39 W |
| South Avery Creek | Stream | | Wapello | 41 05 04 N | 092 31 24 W |
| South Bay | Bay | 374 | Cerro Gordo | 43 06 55 N | 093 24 04 W |