World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Oud-Beijerland | NLOBL | Netherlands |
| Oud-Sabbinge | NLOSG | Netherlands |
| Oud-Turnhout | BEOTH | Belgium |
| Oud-Zuilen | NLOZU | Netherlands |
| Oude Schouw | NLOHW | Netherlands |
| Oudega | NLOGA | Netherlands |
| Oudenaarde | BEOUD | Belgium |
| Oudenburg | BEOBG | Belgium |
| Oudenrijn | NLORJ | Netherlands |
| Oudergem (Auderghem)/Brussel (Bruxelles) | BEODE | Belgium |