| Castaic to Smolyan | 6,689.82 mi (10,766.23 km) |
| Castaic to Sofia | 6,587.83 mi (10,602.10 km) |
| Castaic to Sopot | 6,627.05 mi (10,665.21 km) |
| Castaic to Sozopol | 6,712.94 mi (10,803.43 km) |
| Castaic to Sredets | 6,705.19 mi (10,790.96 km) |
| Castaic to Stamboliyski | 6,652.57 mi (10,706.28 km) |
| Castaic to Stara Zagora | 6,662.53 mi (10,722.30 km) |
| Castaic to Svilengrad | 6,716.47 mi (10,809.11 km) |
| Castaic to Svishtov | 6,583.69 mi (10,595.42 km) |
| Castaic to Targovishte | 6,635.61 mi (10,678.98 km) |
| Castaic to Teteven | 6,598.88 mi (10,619.87 km) |
| Castaic to Troyan | 6,612.20 mi (10,641.32 km) |
| Castaic to Tryavna | 6,632.63 mi (10,674.19 km) |
| Castaic to Tutrakan | 6,587.68 mi (10,601.85 km) |
| Castaic to Varna | 6,668.87 mi (10,732.51 km) |
