Seaports
| Seaport Name | Seaport Code | Country |
|---|---|---|
| Oran | DZORN | Algeria |
| Onslow | AUONS | Australia |
| Ostend | BEOST | Belgium |
| Oostende | BEOST | Belgium |
| Oakville | CAOAK | Canada |
| Ocean Falls | CAOFA | Canada |
| Odense | DKODE | Denmark |
| Oulu | FIOUL | Finland |
| Ostermoor | DEOSR | Germany |
| Otranto | ITOTO | Italy |
| Ortona | ITORT | Italy |
| Okinawa | CNKWN | Japan |
| Oita | JPBPU | Japan |
| Owase | JPOWA | Japan |
| Osaka | JPHAN | Japan |
| Onogawa | JPONG | Japan |
| Omishima | JPIYM | Japan |
| Ofunato | JPOFT | Japan |
| Ocean Island | KIBAN | Kiribati |
| Oranjemund | NAOJM | Namibia |