| Belfast to Oberkirch | 731.23 mi (1,176.80 km) |
| Belfast to Obernburg am Main | 715.65 mi (1,151.72 km) |
| Belfast to Obernkirchen | 638.64 mi (1,027.79 km) |
| Belfast to Oberschleissheim | 868.63 mi (1,397.92 km) |
| Belfast to Oberstdorf | 858.85 mi (1,382.18 km) |
| Belfast to Obertraubling | 862.48 mi (1,388.03 km) |
| Belfast to Obertshausen | 695.66 mi (1,119.55 km) |
| Belfast to Oberursel | 681.02 mi (1,095.99 km) |
| Belfast to Ochsenfurt | 757.45 mi (1,218.99 km) |
| Belfast to Ochsenhausen | 817.49 mi (1,315.62 km) |
| Belfast to Ochtrup | 564.19 mi (907.98 km) |
| Belfast to Odenthal | 596.68 mi (960.27 km) |
| Belfast to Oelde | 611.80 mi (984.59 km) |
| Belfast to Oelsnitz | 811.18 mi (1,305.46 km) |
| Belfast to Oer-Erkenschwick | 582.35 mi (937.20 km) |
