| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Oia | city | Aveiro | Portugal | 40.54 | -8.54 | 226 | 20476 |
| Ois da Ribeira | city | Aveiro | Portugal | 40.58 | -8.50 | 26 | 25628 |
| Ois do Bairro | city | Aveiro | Portugal | 40.43 | -8.48 | 173 | 18747 |
| Oitao | city | Setubal | Portugal | 38.49 | -8.93 | 3 | 19148 |
| Oitavos | city | Lisboa | Portugal | 38.70 | -9.47 | 3 | 42540 |