| Friendswood to Smolyan | 6,208.64 mi (9,991.84 km) |
| Friendswood to Sofia | 6,105.14 mi (9,825.28 km) |
| Friendswood to Sopot | 6,162.18 mi (9,917.07 km) |
| Friendswood to Sozopol | 6,284.51 mi (10,113.94 km) |
| Friendswood to Sredets | 6,268.94 mi (10,088.89 km) |
| Friendswood to Stamboliyski | 6,177.24 mi (9,941.31 km) |
| Friendswood to Stara Zagora | 6,206.46 mi (9,988.34 km) |
| Friendswood to Svilengrad | 6,258.19 mi (10,071.59 km) |
| Friendswood to Svishtov | 6,140.89 mi (9,882.81 km) |
| Friendswood to Targovishte | 6,203.88 mi (9,984.18 km) |
| Friendswood to Teteven | 6,131.59 mi (9,867.84 km) |
| Friendswood to Troyan | 6,150.32 mi (9,897.99 km) |
| Friendswood to Tryavna | 6,180.87 mi (9,947.15 km) |
| Friendswood to Tutrakan | 6,167.92 mi (9,926.31 km) |
| Friendswood to Varna | 6,254.74 mi (10,066.03 km) |
