| Isabela to Smolyan | 5,464.57 mi (8,794.37 km) |
| Isabela to Sofia | 5,377.21 mi (8,653.79 km) |
| Isabela to Sopot | 5,447.91 mi (8,767.57 km) |
| Isabela to Sozopol | 5,596.76 mi (9,007.12 km) |
| Isabela to Sredets | 5,573.65 mi (8,969.92 km) |
| Isabela to Stamboliyski | 5,446.43 mi (8,765.19 km) |
| Isabela to Stara Zagora | 5,496.06 mi (8,845.05 km) |
| Isabela to Svilengrad | 5,535.73 mi (8,908.90 km) |
| Isabela to Svishtov | 5,459.77 mi (8,786.66 km) |
| Isabela to Targovishte | 5,526.19 mi (8,893.54 km) |
| Isabela to Teteven | 5,419.52 mi (8,721.87 km) |
| Isabela to Troyan | 5,442.13 mi (8,758.26 km) |
| Isabela to Tryavna | 5,480.71 mi (8,820.35 km) |
| Isabela to Tutrakan | 5,512.58 mi (8,871.64 km) |
| Isabela to Varna | 5,591.21 mi (8,998.18 km) |
