World Sea Ports
| Port Name | Port Code | Country Name |
|---|---|---|
| Nyrup | DKNR4 | Denmark |
| Nysted | DKNTD | Denmark |
| Nyugawa | JPNWA | Japan |
| Nyukou | JPNYK | Japan |
| Nyuzu | JPNYZ | Japan |
| O'Higgins | CLOHI | Chile |
| Oak Bluffs | USOB2 | United States of America (the) |
| Oak Flats | AUOKF | Australia |
| Oak Grove | USAKJ | United States of America (the) |
| Oak Park | USQOP | United States of America (the) |