World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Ouderkerk aan de Amstel | NLODR | Netherlands |
| Oudeschild | NLOHI | Netherlands |
| Oudna | TNOUD | Tunisia |
| Ouessant | FROS2 | France |
| Ouessant | FRRHP | France |
| Ouesso | CGOUE | Congo |
| Ougrée | BEOUG | Belgium |
| Ouistreham | FROUI | France |
| Oulton Broad | GBOBR | United Kingdom |
| Oupeye | BEOPY | Belgium |