| Abbreviation | Definition |
|---|---|
| OA | Office of Administration |
| OAB | Ocean Affairs Board |
| OAC | Oceanographic Advisory Committee |
| OACES | Ocean Atmosphere Carbon Exchange Study |
| OAE | Ocean Anoxic Events |
| OALOS | Office for Ocean Affairs and the Law of the Sea |
| OAPO | Eastern Pacific Tuna Fishing Organization |
| OAR | Office of Oceanic and Atmospheric Research |
| OAS | Organization of American States |
| OASIS | Ocean Atmosphere Seafloor Integration Study |
| OASIS | Oceanic and Atmospheric Scientific Information System |
| OAUS | Oceanic Australian Undersea Study |
| OB | Outer Banks |
| OBFLW | Outgoing Breakpoint Forced Long Wave |
| OBH | Ocean Bottom Hydrophone Instruments |
| OBM | Ocean Blue Management |
| OBS | Ocean Bottom Seismometer |
| OBS | OSIS (Ocean Surveillance Information System) Baseline System |
| OBU | OSIS Baseline Upgrade |
| OCA | Oceanic Control Area |