| Sliven to Olivenza | 1,761.64 mi (2,835.08 km) |
| Sliven to Olot | 1,212.41 mi (1,951.18 km) |
| Sliven to Onate | 1,449.17 mi (2,332.22 km) |
| Sliven to Onda | 1,387.01 mi (2,232.17 km) |
| Sliven to Onteniente | 1,428.74 mi (2,299.34 km) |
| Sliven to Orihuela | 1,463.64 mi (2,355.50 km) |
| Sliven to Osuna | 1,696.34 mi (2,730.00 km) |
| Sliven to Ourense | 1,729.88 mi (2,783.97 km) |
| Sliven to Oviedo | 1,616.00 mi (2,600.70 km) |
| Sliven to Paiporta | 1,405.77 mi (2,262.37 km) |
| Sliven to Pajara | 2,451.17 mi (3,944.77 km) |
| Sliven to Palafolls | 1,205.63 mi (1,940.28 km) |
| Sliven to Palafrugell | 1,181.54 mi (1,901.51 km) |
| Sliven to Palamos | 1,184.18 mi (1,905.75 km) |
| Sliven to Palencia | 1,568.01 mi (2,523.47 km) |
