| Serris to Smolyan | 1,173.37 mi (1,888.35 km) |
| Serris to Sofia | 1,073.15 mi (1,727.06 km) |
| Serris to Sopot | 1,137.31 mi (1,830.32 km) |
| Serris to Sozopol | 1,276.17 mi (2,053.79 km) |
| Serris to Sredets | 1,256.13 mi (2,021.54 km) |
| Serris to Stamboliyski | 1,145.92 mi (1,844.18 km) |
| Serris to Stara Zagora | 1,184.51 mi (1,906.28 km) |
| Serris to Svilengrad | 1,232.24 mi (1,983.09 km) |
| Serris to Svishtov | 1,132.50 mi (1,822.58 km) |
| Serris to Targovishte | 1,199.15 mi (1,929.85 km) |
| Serris to Teteven | 1,106.91 mi (1,781.39 km) |
| Serris to Troyan | 1,127.93 mi (1,815.22 km) |
| Serris to Tryavna | 1,163.21 mi (1,872.00 km) |
| Serris to Tutrakan | 1,176.45 mi (1,893.32 km) |
| Serris to Varna | 1,260.03 mi (2,027.83 km) |
