| Carrier Code | Carrier Name |
| OCNP | OCEAN TRANSPORT |
| OCNU | OCEAN LINE INC |
| OCNV | OCEAN TRANSPORT SERVICES |
| OCOP | OCEAN OPERATORS INC |
| OCRS | OIL CARRIERS SHIPPING LIMITED |
| OCSG | OLYMPIC OCEAN SHIPPING LIMITED |
| OCSS | OCEANIC STEAMSHIP CO, THE |
| OCTA | OVERSEAS COAL TRANSPORT INC |
| OITS | OIL TRANSPORT SHIPPING LIMITED |
| OKEA | OKEANOPOROS CORPORATION (L) |
| OLAU | OCCIDENTAL CHEMICAL CORPORATION |
| OLEO | OLERON TANKER S A |
| OLGV | OCEAN LONGEVITY CO LTD |
| OLPW | OLYMPIA TANKER CORPORATION |
| OLSH | OLYMPUS STEAMSHIP AGENCIES |
