| Castlebar to Smolyan | 1,769.84 mi (2,848.28 km) |
| Castlebar to Sofia | 1,666.58 mi (2,682.10 km) |
| Castlebar to Sopot | 1,725.02 mi (2,776.15 km) |
| Castlebar to Sozopol | 1,852.87 mi (2,981.90 km) |
| Castlebar to Sredets | 1,835.68 mi (2,954.24 km) |
| Castlebar to Stamboliyski | 1,738.89 mi (2,798.47 km) |
| Castlebar to Stara Zagora | 1,770.18 mi (2,848.82 km) |
| Castlebar to Svilengrad | 1,821.10 mi (2,930.77 km) |
| Castlebar to Svishtov | 1,708.21 mi (2,749.10 km) |
| Castlebar to Targovishte | 1,772.92 mi (2,853.23 km) |
| Castlebar to Teteven | 1,694.37 mi (2,726.82 km) |
| Castlebar to Troyan | 1,713.70 mi (2,757.93 km) |
| Castlebar to Tryavna | 1,745.63 mi (2,809.32 km) |
| Castlebar to Tutrakan | 1,741.49 mi (2,802.66 km) |
| Castlebar to Varna | 1,827.96 mi (2,941.82 km) |
