| Castricum to Smolyan | 1,202.52 mi (1,935.27 km) |
| Castricum to Sofia | 1,098.31 mi (1,767.56 km) |
| Castricum to Sopot | 1,152.59 mi (1,854.91 km) |
| Castricum to Sozopol | 1,274.61 mi (2,051.29 km) |
| Castricum to Sredets | 1,258.56 mi (2,025.46 km) |
| Castricum to Stamboliyski | 1,169.47 mi (1,882.08 km) |
| Castricum to Stara Zagora | 1,196.25 mi (1,925.18 km) |
| Castricum to Svilengrad | 1,248.40 mi (2,009.11 km) |
| Castricum to Svishtov | 1,130.57 mi (1,819.48 km) |
| Castricum to Targovishte | 1,194.17 mi (1,921.83 km) |
| Castricum to Teteven | 1,122.11 mi (1,805.86 km) |
| Castricum to Troyan | 1,140.35 mi (1,835.21 km) |
| Castricum to Tryavna | 1,170.39 mi (1,883.55 km) |
| Castricum to Tutrakan | 1,160.55 mi (1,867.73 km) |
| Castricum to Varna | 1,247.29 mi (2,007.31 km) |
