| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Siddan | city | Meath | Ireland | 53.81 | -6.66 | 209 | 1850 |
| Sillagh | city | Kildare | Ireland | 53.17 | -6.64 | 830 | 10991 |
| Sillahertane | city | Kerry | Ireland | 51.90 | -9.31 | 1023 | 567 |
| Sillahertane | city | Cork | Ireland | 51.72 | -9.22 | 830 | 835 |
| Silloge | city | Meath | Ireland | 53.70 | -6.70 | 226 | 13032 |
| Silver Ford | city | Mayo | Ireland | 53.99 | -9.03 | 334 | 1364 |
| Silver Spring Hotel Conference | city | Cork | Ireland | 51.91 | -8.42 | 203 | 80419 |
| Silver Stream | city | Ireland | 54.27 | -6.92 | 213 | 6382 | |
| Silvermines | city | Ireland | 52.79 | -8.23 | 830 | 1221 | |
| Simonstown | city | An Iarmhi | Ireland | 53.52 | -7.13 | 410 | 2300 |
| Simonstown | city | Meath | Ireland | 53.68 | -6.70 | 157 | 16593 |
| Sinclair's Village | city | Galway | Ireland | 53.30 | -8.26 | 242 | 5274 |
| Sinclair’s Village | city | Galway | Ireland | 53.30 | -8.26 | 242 | 5274 |
| Single Street | city | Donegal | Ireland | 54.48 | -8.26 | 3 | 3249 |
| Siol Ealaigh | city | Wicklow | Ireland | 52.75 | -6.54 | 265 | 2071 |
| Sionainn | city | Clare | Ireland | 52.70 | -8.86 | 0 | 7162 |
| Sir Albert's Bridge | city | Donegal | Ireland | 54.74 | -8.29 | 830 | 1275 |
| Sir Albert’s Bridge | city | Donegal | Ireland | 54.74 | -8.29 | 830 | 1275 |
| Six Crosses | city | Kerry | Ireland | 52.41 | -9.51 | 298 | 5313 |
| Sixmile Bridge | city | Ireland | 52.54 | -8.54 | 249 | 2590 | |
| Sixmilebridge | city | Clare | Ireland | 52.74 | -8.77 | 141 | 3829 |
| Sixmilewater | city | Cork | Ireland | 52.01 | -8.56 | 830 | 2457 |