| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Oandi | city | Hiiumaa | Estonia | 59.0166667 | 22.55 | 22 | 604 |
| Ogandi | city | Hiiumaa | Estonia | 59.0166667 | 22.55 | 22 | 604 |
| Oinigu Kula | city | Hiiumaa | Estonia | 58.8505556 | 22.4663889 | 49 | 755 |
| Oiniku | city | Hiiumaa | Estonia | 58.8505556 | 22.4663889 | 49 | 755 |
| Ole | city | Hiiumaa | Estonia | 58.7672222 | 22.5211111 | 29 | 797 |
| Ongu | city | Hiiumaa | Estonia | 58.8505556 | 22.4663889 | 49 | 755 |
| Or'yaku | city | Hiiumaa | Estonia | 58.7922222 | 22.7819444 | 26 | 677 |
| Orjaku | city | Hiiumaa | Estonia | 58.7922222 | 22.7819444 | 26 | 677 |
| Orjaku Mois | city | Hiiumaa | Estonia | 58.7922222 | 22.7819444 | 26 | 677 |
| Orjaku Mõis | city | Hiiumaa | Estonia | 58.7922222 | 22.7819444 | 26 | 677 |
| Orʼyaku | city | Hiiumaa | Estonia | 58.7922222 | 22.7819444 | 26 | 677 |
| Otste | city | Hiiumaa | Estonia | 58.9697222 | 22.535 | 29 | 724 |
| Ounaku | city | Hiiumaa | Estonia | 58.8372222 | 22.9030556 | 45 | 697 |
| Oyniku | city | Hiiumaa | Estonia | 58.8505556 | 22.4663889 | 49 | 755 |
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