World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Otterndorf | DEOTT | Germany |
| Otternish, North Uist | GBOTR | United Kingdom |
| Ottersøy | NOOTO | Norway |
| Ottersøya | NOOTA | Norway |
| Ottmarsheim | FROTM | France |
| Ottsville | USOSV | United States of America (the) |
| Ottumwa | USOTM | United States of America (the) |
| Ouanary | GFLCY | French Guiana |
| Oud Gein | NLOGN | Netherlands |
| Oud-Alblas | NLA2Z | Netherlands |