| Castleford to Smolyan | 1,460.93 mi (2,351.15 km) |
| Castleford to Sofia | 1,356.94 mi (2,183.79 km) |
| Castleford to Sopot | 1,412.68 mi (2,273.49 km) |
| Castleford to Sozopol | 1,536.37 mi (2,472.55 km) |
| Castleford to Sredets | 1,520.05 mi (2,446.29 km) |
| Castleford to Stamboliyski | 1,428.58 mi (2,299.08 km) |
| Castleford to Stara Zagora | 1,456.84 mi (2,344.56 km) |
| Castleford to Svilengrad | 1,508.65 mi (2,427.93 km) |
| Castleford to Svishtov | 1,392.14 mi (2,240.44 km) |
| Castleford to Targovishte | 1,456.01 mi (2,343.22 km) |
| Castleford to Teteven | 1,382.12 mi (2,224.32 km) |
| Castleford to Troyan | 1,400.72 mi (2,254.24 km) |
| Castleford to Tryavna | 1,431.34 mi (2,303.52 km) |
| Castleford to Tutrakan | 1,422.74 mi (2,289.67 km) |
| Castleford to Varna | 1,509.45 mi (2,429.22 km) |
