| Difficult Run to Cocentaina | 4,004.56 mi (6,444.71 km) |
| Difficult Run to Coin | 3,857.20 mi (6,207.57 km) |
| Difficult Run to Colindres | 3,728.62 mi (6,000.64 km) |
| Difficult Run to Collado-Villalba | 3,777.34 mi (6,079.05 km) |
| Difficult Run to Colmenar Viejo | 3,788.24 mi (6,096.58 km) |
| Difficult Run to Colmenarejo | 3,778.97 mi (6,081.66 km) |
| Difficult Run to Conil de la Frontera | 3,802.78 mi (6,119.98 km) |
| Difficult Run to Consuegra | 3,830.15 mi (6,164.04 km) |
| Difficult Run to Corbera de Llobregat | 4,034.97 mi (6,493.65 km) |
| Difficult Run to Cordoba | 3,819.15 mi (6,146.32 km) |
| Difficult Run to Coria del Rio | 3,774.07 mi (6,073.77 km) |
| Difficult Run to Crevillente | 4,002.14 mi (6,440.83 km) |
| Difficult Run to Cuarte de Huerva | 3,896.94 mi (6,271.51 km) |
| Difficult Run to Cubellas | 4,029.25 mi (6,484.45 km) |
| Difficult Run to Cuellar | 3,741.50 mi (6,021.36 km) |
