| Holyhead to Octeville | 285.04 mi (458.73 km) |
| Holyhead to Oignies | 379.53 mi (610.80 km) |
| Holyhead to Oissel | 368.85 mi (593.60 km) |
| Holyhead to Olivet | 472.55 mi (760.49 km) |
| Holyhead to Ollioules | 850.39 mi (1,368.56 km) |
| Holyhead to Olonne-sur-Mer | 484.85 mi (780.28 km) |
| Holyhead to Oloron-Sainte-Marie | 722.70 mi (1,163.07 km) |
| Holyhead to Onet Village | 699.06 mi (1,125.02 km) |
| Holyhead to Onnaing | 404.81 mi (651.49 km) |
| Holyhead to Orange | 764.57 mi (1,230.45 km) |
| Holyhead to Orchies | 388.49 mi (625.22 km) |
| Holyhead to Orleans | 470.58 mi (757.33 km) |
| Holyhead to Orly | 438.59 mi (705.85 km) |
| Holyhead to Ormesson-sur-Marne | 440.85 mi (709.47 km) |
| Holyhead to Orsay | 434.86 mi (699.85 km) |
