| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
| Oa | city | State of Pohnpei | Federated States of Micronesia | 6.9166667 | 158.3147222 | 0 | 8274 |
| Oarmoar | city | State of Pohnpei | Federated States of Micronesia | 6.9352778 | 158.1680556 | 479 | 16651 |
| Oaumoar | city | State of Pohnpei | Federated States of Micronesia | 6.9352778 | 158.1680556 | 479 | 16651 |
| Oaunoar | city | State of Pohnpei | Federated States of Micronesia | 6.9352778 | 158.1680556 | 479 | 16651 |
| Oboen | city | State of Chuuk | Federated States of Micronesia | 7.3336111 | 151.8366667 | 3 | 3575 |
| Ohwa | city | State of Pohnpei | Federated States of Micronesia | 6.9166667 | 158.3147222 | 0 | 8274 |
| Okau | city | State of Yap | Federated States of Micronesia | 9.5333333 | 138.1 | 344 | 9469 |
| Olip | city | State of Chuuk | Federated States of Micronesia | 7.3316667 | 151.6066667 | 1249 | 4212 |
| Omin | city | State of Yap | Federated States of Micronesia | 9.6 | 138.15 | 131 | 5838 |
| Omin | city | State of Yap | Federated States of Micronesia | 9.6002778 | 138.1652778 | 82 | 5838 |
| Onean | city | State of Pohnpei | Federated States of Micronesia | 6.8205556 | 158.2752778 | 85 | 13584 |
| Onip | city | State of Chuuk | Federated States of Micronesia | 7.3316667 | 151.6066667 | 1249 | 4212 |
| Onip | city | State of Chuuk | Federated States of Micronesia | 7.3766667 | 151.7313889 | 0 | 906 |
| Onongoch | city | State of Chuuk | Federated States of Micronesia | 7.35 | 151.8333333 | 3 | 2646 |
| Onongot | city | State of Chuuk | Federated States of Micronesia | 7.35 | 151.8333333 | 3 | 2646 |
| Opun | city | State of Chuuk | Federated States of Micronesia | 7.3525 | 151.7816667 | 0 | 1494 |
| Orila | city | State of Yap | Federated States of Micronesia | 9.5825 | 138.1555556 | 6 | 9812 |
| Orile | city | State of Yap | Federated States of Micronesia | 9.5825 | 138.1555556 | 6 | 9812 |
| Orira | city | State of Yap | Federated States of Micronesia | 9.5825 | 138.1555556 | 6 | 9812 |
| Oror en Fein | city | State of Chuuk | Federated States of Micronesia | 7.3475 | 151.8341667 | 3 | 3575 |
| Orowoo | city | State of Yap | Federated States of Micronesia | 9.5091667 | 138.1283333 | 0 | 9333 |
| Oumoar | city | State of Pohnpei | Federated States of Micronesia | 6.9352778 | 158.1680556 | 479 | 16651 |