World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Oleum | USOL2 | United States of America (the) |
| Olhão | PTOLH | Portugal |
| Olhos de Água | PTOLA | Portugal |
| Olias del Rey | ESOLY | Spain |
| Oliver | CAOVR | Canada |
| Olivette | USZOT | United States of America (the) |
| Olkiluoto | FIOLK | Finland |
| Ollignies | BEOGS | Belgium |
| Olongapo | PHOLO | Philippines (the) |
| Olonzac | FR43H | France |