| Romanshorn to Smolyan | 858.68 mi (1,381.92 km) |
| Romanshorn to Sofia | 758.01 mi (1,219.89 km) |
| Romanshorn to Sopot | 821.99 mi (1,322.87 km) |
| Romanshorn to Sozopol | 961.41 mi (1,547.24 km) |
| Romanshorn to Sredets | 941.12 mi (1,514.59 km) |
| Romanshorn to Stamboliyski | 830.80 mi (1,337.04 km) |
| Romanshorn to Stara Zagora | 869.21 mi (1,398.87 km) |
| Romanshorn to Svilengrad | 916.94 mi (1,475.68 km) |
| Romanshorn to Svishtov | 818.17 mi (1,316.71 km) |
| Romanshorn to Targovishte | 884.93 mi (1,424.16 km) |
| Romanshorn to Teteven | 791.60 mi (1,273.95 km) |
| Romanshorn to Troyan | 812.65 mi (1,307.84 km) |
| Romanshorn to Tryavna | 848.08 mi (1,364.86 km) |
| Romanshorn to Tutrakan | 863.96 mi (1,390.41 km) |
| Romanshorn to Varna | 946.61 mi (1,523.43 km) |
