| Bilbao to Smolyan | 1,407.27 mi (2,264.78 km) |
| Bilbao to Sofia | 1,322.19 mi (2,127.87 km) |
| Bilbao to Sopot | 1,393.67 mi (2,242.90 km) |
| Bilbao to Sozopol | 1,543.95 mi (2,484.75 km) |
| Bilbao to Sredets | 1,520.06 mi (2,446.30 km) |
| Bilbao to Stamboliyski | 1,390.19 mi (2,237.30 km) |
| Bilbao to Stara Zagora | 1,441.56 mi (2,319.97 km) |
| Bilbao to Svilengrad | 1,479.36 mi (2,380.80 km) |
| Bilbao to Svishtov | 1,411.84 mi (2,272.14 km) |
| Bilbao to Targovishte | 1,477.07 mi (2,377.11 km) |
| Bilbao to Teteven | 1,366.15 mi (2,198.61 km) |
| Bilbao to Troyan | 1,388.97 mi (2,235.33 km) |
| Bilbao to Tryavna | 1,428.15 mi (2,298.38 km) |
| Bilbao to Tutrakan | 1,469.83 mi (2,365.47 km) |
| Bilbao to Varna | 1,543.48 mi (2,483.99 km) |
