| Difficult Run to Octeville | 3,656.54 mi (5,884.63 km) |
| Difficult Run to Oignies | 3,829.59 mi (6,163.13 km) |
| Difficult Run to Oissel | 3,778.62 mi (6,081.11 km) |
| Difficult Run to Olivet | 3,850.58 mi (6,196.92 km) |
| Difficult Run to Ollioules | 4,160.68 mi (6,695.97 km) |
| Difficult Run to Olonne-sur-Mer | 3,724.30 mi (5,993.67 km) |
| Difficult Run to Oloron-Sainte-Marie | 3,865.52 mi (6,220.95 km) |
| Difficult Run to Onet Village | 3,977.63 mi (6,401.38 km) |
| Difficult Run to Onnaing | 3,856.40 mi (6,206.28 km) |
| Difficult Run to Orange | 4,083.43 mi (6,571.64 km) |
| Difficult Run to Orchies | 3,839.71 mi (6,179.42 km) |
| Difficult Run to Orleans | 3,849.93 mi (6,195.87 km) |
| Difficult Run to Orly | 3,848.59 mi (6,193.71 km) |
| Difficult Run to Ormesson-sur-Marne | 3,853.65 mi (6,201.84 km) |
| Difficult Run to Orsay | 3,841.10 mi (6,181.65 km) |
