| Opmeer to Navodari | 1,220.19 mi (1,963.70 km) |
| Opmeer to Negresti-Oas | 878.12 mi (1,413.20 km) |
| Opmeer to Nehoiu | 1,086.81 mi (1,749.04 km) |
| Opmeer to Ocna Mures | 949.35 mi (1,527.83 km) |
| Opmeer to Odobesti | 1,100.87 mi (1,771.68 km) |
| Opmeer to Odorheiu Secuiesc | 1,009.43 mi (1,624.52 km) |
| Opmeer to Oltenita | 1,152.62 mi (1,854.96 km) |
| Opmeer to Onesti | 1,070.33 mi (1,722.54 km) |
| Opmeer to Oradea | 846.85 mi (1,362.87 km) |
| Opmeer to Orastie | 945.22 mi (1,521.19 km) |
| Opmeer to Oravita | 923.02 mi (1,485.47 km) |
| Opmeer to Orsova | 963.56 mi (1,550.71 km) |
| Opmeer to Otelu Rosu | 926.81 mi (1,491.56 km) |
| Opmeer to Otopeni | 1,110.79 mi (1,787.64 km) |
| Opmeer to Ovidiu | 1,220.19 mi (1,963.71 km) |
