| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Oandu | city | Ida-Virumaa | Estonia | 59.2641667 | 27.0105556 | 193 | 4688 |
| Obhonja | city | Ida-Virumaa | Estonia | 59.094444 | 27.4775 | 167 | 4712 |
| Ohakvere | city | Ida-Virumaa | Estonia | 59.2280556 | 27.4663889 | 216 | 4697 |
| Olgina | city | Ida-Virumaa | Estonia | 59.3952778 | 28.1252778 | 114 | 3282 |
| Ongassaare | city | Ida-Virumaa | Estonia | 59.1969444 | 27.4747222 | 209 | 4702 |
| Ontika | city | Ida-Virumaa | Estonia | 59.4347222 | 27.2911111 | 170 | 2832 |
| Ontika Asundus | city | Ida-Virumaa | Estonia | 59.4347222 | 27.2911111 | 170 | 2832 |
| Ontika-Saka | city | Ida-Virumaa | Estonia | 59.4338889 | 27.2463889 | 177 | 2734 |
| Onurme | city | Ida-Virumaa | Estonia | 59.1136111 | 26.9216667 | 200 | 4521 |
| Oonurme | city | Ida-Virumaa | Estonia | 59.1136111 | 26.9216667 | 200 | 4521 |
| Oru | city | Ida-Virumaa | Estonia | 59.4463889 | 26.8077778 | 137 | 3810 |
| Oru | city | Ida-Virumaa | Estonia | 59.3675 | 27.5694444 | 127 | 4680 |
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