| Ridderkerk to Smolyan | 1,181.33 mi (1,901.16 km) |
| Ridderkerk to Sofia | 1,077.36 mi (1,733.84 km) |
| Ridderkerk to Sopot | 1,133.44 mi (1,824.10 km) |
| Ridderkerk to Sozopol | 1,258.69 mi (2,025.66 km) |
| Ridderkerk to Sredets | 1,241.92 mi (1,998.67 km) |
| Ridderkerk to Stamboliyski | 1,149.05 mi (1,849.22 km) |
| Ridderkerk to Stara Zagora | 1,177.85 mi (1,895.57 km) |
| Ridderkerk to Svilengrad | 1,229.46 mi (1,978.62 km) |
| Ridderkerk to Svishtov | 1,114.19 mi (1,793.12 km) |
| Ridderkerk to Targovishte | 1,178.55 mi (1,896.69 km) |
| Ridderkerk to Teteven | 1,102.86 mi (1,774.88 km) |
| Ridderkerk to Troyan | 1,121.62 mi (1,805.08 km) |
| Ridderkerk to Tryavna | 1,152.64 mi (1,854.99 km) |
| Ridderkerk to Tutrakan | 1,146.67 mi (1,845.38 km) |
| Ridderkerk to Varna | 1,233.17 mi (1,984.59 km) |
