| Solothurn to Smolyan | 929.93 mi (1,496.58 km) |
| Solothurn to Sofia | 831.12 mi (1,337.56 km) |
| Solothurn to Sopot | 896.97 mi (1,443.54 km) |
| Solothurn to Sozopol | 1,039.07 mi (1,672.22 km) |
| Solothurn to Sredets | 1,018.09 mi (1,638.46 km) |
| Solothurn to Stamboliyski | 903.70 mi (1,454.37 km) |
| Solothurn to Stara Zagora | 944.65 mi (1,520.26 km) |
| Solothurn to Svilengrad | 991.01 mi (1,594.87 km) |
| Solothurn to Svishtov | 896.93 mi (1,443.47 km) |
| Solothurn to Targovishte | 963.79 mi (1,551.07 km) |
| Solothurn to Teteven | 866.85 mi (1,395.07 km) |
| Solothurn to Troyan | 888.38 mi (1,429.70 km) |
| Solothurn to Tryavna | 924.70 mi (1,488.16 km) |
| Solothurn to Tutrakan | 944.99 mi (1,520.81 km) |
| Solothurn to Varna | 1,026.52 mi (1,652.03 km) |
