| Willoughby to Smolyan | 5,070.30 mi (8,159.85 km) |
| Willoughby to Sofia | 4,966.71 mi (7,993.15 km) |
| Willoughby to Sopot | 5,023.51 mi (8,084.56 km) |
| Willoughby to Sozopol | 5,145.80 mi (8,281.37 km) |
| Willoughby to Sredets | 5,130.19 mi (8,256.25 km) |
| Willoughby to Stamboliyski | 5,038.74 mi (8,109.07 km) |
| Willoughby to Stara Zagora | 5,067.74 mi (8,155.73 km) |
| Willoughby to Svilengrad | 5,119.51 mi (8,239.05 km) |
| Willoughby to Svishtov | 5,002.15 mi (8,050.18 km) |
| Willoughby to Targovishte | 5,065.19 mi (8,151.64 km) |
| Willoughby to Teteven | 4,992.93 mi (8,035.34 km) |
| Willoughby to Troyan | 5,011.62 mi (8,065.42 km) |
| Willoughby to Tryavna | 5,042.12 mi (8,114.50 km) |
| Willoughby to Tutrakan | 5,029.43 mi (8,094.09 km) |
| Willoughby to Varna | 5,116.26 mi (8,233.83 km) |
