| Ostend to Navodari | 1,276.69 mi (2,054.64 km) |
| Ostend to Negresti-Oas | 944.59 mi (1,520.17 km) |
| Ostend to Nehoiu | 1,143.10 mi (1,839.63 km) |
| Ostend to Ocna Mures | 1,005.60 mi (1,618.35 km) |
| Ostend to Odobesti | 1,161.89 mi (1,869.88 km) |
| Ostend to Odorheiu Secuiesc | 1,069.32 mi (1,720.90 km) |
| Ostend to Oltenita | 1,202.03 mi (1,934.47 km) |
| Ostend to Onesti | 1,133.74 mi (1,824.58 km) |
| Ostend to Oradea | 902.40 mi (1,452.27 km) |
| Ostend to Orastie | 995.32 mi (1,601.82 km) |
| Ostend to Oravita | 961.42 mi (1,547.25 km) |
| Ostend to Orsova | 1,002.45 mi (1,613.29 km) |
| Ostend to Otelu Rosu | 971.42 mi (1,563.34 km) |
| Ostend to Otopeni | 1,161.28 mi (1,868.90 km) |
| Ostend to Ovidiu | 1,276.26 mi (2,053.95 km) |
