| Letterkenny to Smolyan | 1,730.76 mi (2,785.38 km) |
| Letterkenny to Sofia | 1,626.84 mi (2,618.15 km) |
| Letterkenny to Sopot | 1,682.85 mi (2,708.29 km) |
| Letterkenny to Sozopol | 1,806.37 mi (2,907.08 km) |
| Letterkenny to Sredets | 1,790.17 mi (2,881.00 km) |
| Letterkenny to Stamboliyski | 1,698.58 mi (2,733.60 km) |
| Letterkenny to Stara Zagora | 1,727.05 mi (2,779.41 km) |
| Letterkenny to Svilengrad | 1,778.83 mi (2,862.75 km) |
| Letterkenny to Svishtov | 1,662.23 mi (2,675.10 km) |
| Letterkenny to Targovishte | 1,725.96 mi (2,777.67 km) |
| Letterkenny to Teteven | 1,652.29 mi (2,659.10 km) |
| Letterkenny to Troyan | 1,670.92 mi (2,689.08 km) |
| Letterkenny to Tryavna | 1,701.54 mi (2,738.37 km) |
| Letterkenny to Tutrakan | 1,692.24 mi (2,723.40 km) |
| Letterkenny to Varna | 1,779.00 mi (2,863.03 km) |
