| Biddeford to Smolyan | 4,555.32 mi (7,331.09 km) |
| Biddeford to Sofia | 4,452.79 mi (7,166.08 km) |
| Biddeford to Sopot | 4,512.51 mi (7,262.19 km) |
| Biddeford to Sozopol | 4,640.73 mi (7,468.54 km) |
| Biddeford to Sredets | 4,623.69 mi (7,441.11 km) |
| Biddeford to Stamboliyski | 4,525.38 mi (7,282.89 km) |
| Biddeford to Stara Zagora | 4,557.96 mi (7,335.33 km) |
| Biddeford to Svilengrad | 4,608.55 mi (7,416.75 km) |
| Biddeford to Svishtov | 4,496.15 mi (7,235.85 km) |
| Biddeford to Targovishte | 4,560.63 mi (7,339.63 km) |
| Biddeford to Teteven | 4,481.85 mi (7,212.84 km) |
| Biddeford to Troyan | 4,501.41 mi (7,244.32 km) |
| Biddeford to Tryavna | 4,533.61 mi (7,296.15 km) |
| Biddeford to Tutrakan | 4,528.05 mi (7,287.20 km) |
| Biddeford to Varna | 4,614.74 mi (7,426.71 km) |
