| Boulder to Carmona | 5,055.08 mi (8,135.36 km) |
| Boulder to Cartagena | 5,247.34 mi (8,444.77 km) |
| Boulder to Cartama | 5,130.78 mi (8,257.20 km) |
| Boulder to Cartaya | 4,996.83 mi (8,041.62 km) |
| Boulder to Caspe | 5,124.91 mi (8,247.74 km) |
| Boulder to Cassa de la Selva | 5,209.72 mi (8,384.23 km) |
| Boulder to Castalla | 5,215.95 mi (8,394.26 km) |
| Boulder to Castellbisbal | 5,193.71 mi (8,358.47 km) |
| Boulder to Castelldefels | 5,202.39 mi (8,372.43 km) |
| Boulder to Castello de Ampurias | 5,200.64 mi (8,369.62 km) |
| Boulder to Castellon de la Plana | 5,180.39 mi (8,337.03 km) |
| Boulder to Castilleja de la Cuesta | 5,040.56 mi (8,111.99 km) |
| Boulder to Catarroja | 5,191.08 mi (8,354.23 km) |
| Boulder to Catral | 5,229.83 mi (8,416.60 km) |
| Boulder to Caudete | 5,198.05 mi (8,365.45 km) |
