| Carrier Code | Carrier Name |
| OLSS | OLYMPIC STEAMSHIP CO |
| OLTU | OCEANS LEASING & LOGISTICS LTD |
| OLVN | OLIVE NAVIGATION LTD |
| OLYU | OLYMPIC CONTAINER CORP |
| OMAU | OCEAN MARINE LINE |
| OMCP | ORION MARINE CORPORATION |
| OMEU | ODOM MARITIME ENTERPRISES |
| OMIL | OMI PETROLINK CORP |
| OMIN | OCEAN MANAGEMENT INC |
| OMNL | OMNITAINER LINE INC |
| OMRL | OCEANIC MARINE LIMITED |
| OMSG | OMNI SHIPPING INC |
| ONBE | ONBEGO COMPANY S A |
| ONDA | ONDA NAVIGATION INC |
| ONEQ | O N E SHIPPING INC |
