| Donostia to Smolyan | 1,359.62 mi (2,188.09 km) |
| Donostia to Sofia | 1,274.56 mi (2,051.21 km) |
| Donostia to Sopot | 1,346.05 mi (2,166.26 km) |
| Donostia to Sozopol | 1,496.36 mi (2,408.15 km) |
| Donostia to Sredets | 1,472.45 mi (2,369.68 km) |
| Donostia to Stamboliyski | 1,342.54 mi (2,160.61 km) |
| Donostia to Stara Zagora | 1,393.94 mi (2,243.33 km) |
| Donostia to Svilengrad | 1,431.70 mi (2,304.10 km) |
| Donostia to Svishtov | 1,364.39 mi (2,195.77 km) |
| Donostia to Targovishte | 1,429.57 mi (2,300.67 km) |
| Donostia to Teteven | 1,318.55 mi (2,122.01 km) |
| Donostia to Troyan | 1,341.37 mi (2,158.73 km) |
| Donostia to Tryavna | 1,380.57 mi (2,221.81 km) |
| Donostia to Tutrakan | 1,422.53 mi (2,289.33 km) |
| Donostia to Varna | 1,496.01 mi (2,407.60 km) |
