| Abbreviation | Definition |
|---|---|
| OSTAC | Ocean Science and Technology Advisory Committee |
| OSTC | Ocean Science and Technology Cell |
| OSTP | Office of Science and Technology Policy |
| OSU | Office of Systems Operations |
| OT | Office of Telecommunications |
| OT&E | Operational Testing And Evaluation |
| OTA | Office of Technology Assessment |
| OTEC | Ocean Thermal Energy Conversion |
| OTH | Over the Horizon |
| OU | University of Oklahoma, Norman |
| OUE | Ontario Underwater Explorers |
| OUR | Oxygen Utilization Rate |
| OVPQ | Offshore Vessel Particulars Questionnaire |
| OW | Open Water |
| OWD | Open Water Dive |
| OWQP | Optimal Water Quality Parameters |
| OWS | Ocean Weather Station |
| OWST | Open Water Spill Team |
| OXY-WATER | OXYgenated WATER |
| OY | Optimum Yield |