| Difficult Run to Oberkirch | 4,092.22 mi (6,585.80 km) |
| Difficult Run to Obernburg am Main | 4,096.62 mi (6,592.87 km) |
| Difficult Run to Obernkirchen | 4,025.60 mi (6,478.57 km) |
| Difficult Run to Oberschleissheim | 4,243.93 mi (6,829.95 km) |
| Difficult Run to Oberstdorf | 4,217.71 mi (6,787.75 km) |
| Difficult Run to Obertraubling | 4,245.30 mi (6,832.14 km) |
| Difficult Run to Obertshausen | 4,077.55 mi (6,562.19 km) |
| Difficult Run to Oberursel | 4,063.28 mi (6,539.21 km) |
| Difficult Run to Ochsenfurt | 4,139.54 mi (6,661.94 km) |
| Difficult Run to Ochsenhausen | 4,183.20 mi (6,732.21 km) |
| Difficult Run to Ochtrup | 3,952.44 mi (6,360.84 km) |
| Difficult Run to Odenthal | 3,981.40 mi (6,407.44 km) |
| Difficult Run to Oelde | 4,000.09 mi (6,437.52 km) |
| Difficult Run to Oelsnitz | 4,199.35 mi (6,758.20 km) |
| Difficult Run to Oer-Erkenschwick | 3,970.04 mi (6,389.16 km) |
