| Dublin to Oria | 1,423.37 mi (2,290.69 km) |
| Dublin to Oristano | 1,161.05 mi (1,868.53 km) |
| Dublin to Orta Nova | 1,312.73 mi (2,112.64 km) |
| Dublin to Orte | 1,139.24 mi (1,833.43 km) |
| Dublin to Ortona | 1,215.19 mi (1,955.65 km) |
| Dublin to Orvieto | 1,116.62 mi (1,797.02 km) |
| Dublin to Orzinuovi | 908.89 mi (1,462.71 km) |
| Dublin to Osimo | 1,127.03 mi (1,813.78 km) |
| Dublin to Ospitaletto | 906.61 mi (1,459.04 km) |
| Dublin to Ostuni | 1,409.88 mi (2,268.99 km) |
| Dublin to Ottaviano | 1,294.12 mi (2,082.69 km) |
| Dublin to Ovada | 901.71 mi (1,451.16 km) |
| Dublin to Ozieri | 1,133.43 mi (1,824.07 km) |
| Dublin to Paceco | 1,388.46 mi (2,234.52 km) |
| Dublin to Pachino | 1,539.97 mi (2,478.34 km) |
