| Boulder to Sesena | 5,024.80 mi (8,086.63 km) |
| Boulder to Sestao | 4,916.56 mi (7,912.44 km) |
| Boulder to Sevilla | 5,049.23 mi (8,125.95 km) |
| Boulder to Sevilla La Nueva | 5,000.68 mi (8,047.81 km) |
| Boulder to Silla | 5,192.66 mi (8,356.78 km) |
| Boulder to Silleda | 4,729.21 mi (7,610.93 km) |
| Boulder to Sitges | 5,197.69 mi (8,364.87 km) |
| Boulder to Socuellamos | 5,097.26 mi (8,203.25 km) |
| Boulder to Soller | 5,299.85 mi (8,529.28 km) |
| Boulder to Solsona | 5,152.24 mi (8,291.73 km) |
| Boulder to Son Servera | 5,332.74 mi (8,582.22 km) |
| Boulder to Sonseca | 5,031.55 mi (8,097.50 km) |
| Boulder to Sopelana | 4,914.62 mi (7,909.32 km) |
| Boulder to Soria | 5,003.97 mi (8,053.11 km) |
| Boulder to Suances | 4,869.77 mi (7,837.14 km) |
