| Difficult Run to Cernavoda | 5,048.40 mi (8,124.62 km) |
| Difficult Run to Chitila | 4,961.14 mi (7,984.19 km) |
| Difficult Run to Cisnadie | 4,839.88 mi (7,789.03 km) |
| Difficult Run to Cluj-Napoca | 4,775.55 mi (7,685.51 km) |
| Difficult Run to Codlea | 4,890.91 mi (7,871.16 km) |
| Difficult Run to Comanesti | 4,899.32 mi (7,884.69 km) |
| Difficult Run to Comarnic | 4,916.73 mi (7,912.72 km) |
| Difficult Run to Constanta | 5,079.00 mi (8,173.85 km) |
| Difficult Run to Corabia | 4,932.89 mi (7,938.72 km) |
| Difficult Run to Costesti | 4,911.05 mi (7,903.58 km) |
| Difficult Run to Covasna | 4,913.27 mi (7,907.14 km) |
| Difficult Run to Craiova | 4,882.53 mi (7,857.67 km) |
| Difficult Run to Cristuru Secuiesc | 4,850.77 mi (7,806.56 km) |
| Difficult Run to Cugir | 4,803.76 mi (7,730.90 km) |
| Difficult Run to Cumpana | 5,078.32 mi (8,172.77 km) |
