World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Okubo, Kagoshima | JPOOJ | Japan |
| Okubo, Tokyo | JPOKB | Japan |
| Okunouchi | JPOCH | Japan |
| Okwori | NGOKW | Nigeria |
| Ol'ga | RUOLP | Russian Federation (the) |
| Olafsfjørdur | ISOLF | Iceland |
| Olafsvík | ISOLV | Iceland |
| Olah Jasa Andal/Jakarta | IDOJA | Indonesia |
| Olavarría | AROVI | Argentina |
| Olawa | PLOLA | Poland |