| Belfast to Octeville | 388.39 mi (625.06 km) |
| Belfast to Oignies | 470.57 mi (757.31 km) |
| Belfast to Oissel | 469.78 mi (756.05 km) |
| Belfast to Olivet | 574.73 mi (924.93 km) |
| Belfast to Ollioules | 952.81 mi (1,533.39 km) |
| Belfast to Olonne-sur-Mer | 585.77 mi (942.71 km) |
| Belfast to Oloron-Sainte-Marie | 823.50 mi (1,325.29 km) |
| Belfast to Onet Village | 802.45 mi (1,291.43 km) |
| Belfast to Onnaing | 494.52 mi (795.86 km) |
| Belfast to Orange | 867.15 mi (1,395.54 km) |
| Belfast to Orchies | 478.72 mi (770.42 km) |
| Belfast to Orleans | 572.71 mi (921.68 km) |
| Belfast to Orly | 538.45 mi (866.55 km) |
| Belfast to Ormesson-sur-Marne | 540.31 mi (869.54 km) |
| Belfast to Orsay | 535.21 mi (861.35 km) |
