| Killarney to Oria | 1,508.86 mi (2,428.28 km) |
| Killarney to Oristano | 1,202.06 mi (1,934.53 km) |
| Killarney to Orta Nova | 1,395.41 mi (2,245.70 km) |
| Killarney to Orte | 1,214.79 mi (1,955.01 km) |
| Killarney to Ortona | 1,298.44 mi (2,089.64 km) |
| Killarney to Orvieto | 1,192.55 mi (1,919.22 km) |
| Killarney to Orzinuovi | 994.02 mi (1,599.73 km) |
| Killarney to Osimo | 1,213.50 mi (1,952.94 km) |
| Killarney to Ospitaletto | 993.59 mi (1,599.03 km) |
| Killarney to Ostuni | 1,496.33 mi (2,408.11 km) |
| Killarney to Ottaviano | 1,369.38 mi (2,203.80 km) |
| Killarney to Ovada | 974.56 mi (1,568.41 km) |
| Killarney to Ozieri | 1,180.62 mi (1,900.02 km) |
| Killarney to Paceco | 1,440.70 mi (2,318.58 km) |
| Killarney to Pachino | 1,598.26 mi (2,572.15 km) |
