World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Osetoyanagi | JPOST | Japan |
| Oshawa | CAOSH | Canada |
| Oshidomari | JPOSD | Japan |
| Ôshima, Nagasaki | JPOSM | Japan |
| Oshima, Yamaguchi | JPOSL | Japan |
| Osice | CZOSI | Czechia |
| Osijek | HROSI | Croatia |
| Osik | CZPAO | Czechia |
| Osinów Dolny | PLOSD | Poland |
| Oskaloosa | USOS3 | United States of America (the) |