| Boise to Smolyan | 6,071.23 mi (9,770.71 km) |
| Boise to Sofia | 5,970.33 mi (9,608.32 km) |
| Boise to Sopot | 6,006.83 mi (9,667.07 km) |
| Boise to Sozopol | 6,087.63 mi (9,797.09 km) |
| Boise to Sredets | 6,080.84 mi (9,786.17 km) |
| Boise to Stamboliyski | 6,033.52 mi (9,710.01 km) |
| Boise to Stara Zagora | 6,040.90 mi (9,721.89 km) |
| Boise to Svilengrad | 6,094.69 mi (9,808.46 km) |
| Boise to Svishtov | 5,961.04 mi (9,593.37 km) |
| Boise to Targovishte | 6,011.25 mi (9,674.17 km) |
| Boise to Teteven | 5,979.21 mi (9,622.61 km) |
| Boise to Troyan | 5,991.72 mi (9,642.75 km) |
| Boise to Tryavna | 6,010.70 mi (9,673.29 km) |
| Boise to Tutrakan | 5,962.30 mi (9,595.39 km) |
| Boise to Varna | 6,042.28 mi (9,724.12 km) |
