| Kastamonu to Smolyan | 469.83 mi (756.12 km) |
| Kastamonu to Sofia | 543.44 mi (874.58 km) |
| Kastamonu to Sopot | 471.41 mi (758.67 km) |
| Kastamonu to Sozopol | 320.59 mi (515.94 km) |
| Kastamonu to Sredets | 344.93 mi (555.10 km) |
| Kastamonu to Stamboliyski | 479.05 mi (770.95 km) |
| Kastamonu to Stara Zagora | 424.04 mi (682.43 km) |
| Kastamonu to Svilengrad | 392.43 mi (631.55 km) |
| Kastamonu to Svishtov | 456.07 mi (733.97 km) |
| Kastamonu to Targovishte | 389.49 mi (626.83 km) |
| Kastamonu to Teteven | 498.36 mi (802.03 km) |
| Kastamonu to Troyan | 475.51 mi (765.25 km) |
| Kastamonu to Tryavna | 436.27 mi (702.11 km) |
| Kastamonu to Tutrakan | 407.52 mi (655.84 km) |
| Kastamonu to Varna | 325.25 mi (523.44 km) |
