Scuba Diving
| Abbreviation | Meaning | Tamil Meaning | Category |
|---|---|---|---|
| OAO | Orbiting Astronomical Observatory | - | Scuba Diving |
| OSO | Orbiting Solar Observatory | - | Scuba Diving |
| OSS | Office Of Space Science (NASA) | - | Scuba Diving |
| OSSE | Office Of Space Science Education (SSEC) | - | Scuba Diving |