World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Oakboro | USYOB | United States of America (the) |
| Oakhamness | GBOAK | United Kingdom |
| Oakland | USOAK | United States of America (the) |
| Oakville | CAOAJ | Canada |
| Oakville | CAOAK | Canada |
| Oakville | USOKV | United States of America (the) |
| Oarai | JPOAR | Japan |
| Oaxen | SEOAX | Sweden |
| Obama, Fukui | JPOBM | Japan |
| Obama, Mie | JPOBA | Japan |