| Groningen to Navodari | 1,169.94 mi (1,882.84 km) |
| Groningen to Negresti-Oas | 824.54 mi (1,326.97 km) |
| Groningen to Nehoiu | 1,037.21 mi (1,669.22 km) |
| Groningen to Ocna Mures | 900.50 mi (1,449.21 km) |
| Groningen to Odobesti | 1,048.87 mi (1,687.99 km) |
| Groningen to Odorheiu Secuiesc | 958.41 mi (1,542.41 km) |
| Groningen to Oltenita | 1,106.20 mi (1,780.26 km) |
| Groningen to Onesti | 1,017.28 mi (1,637.16 km) |
| Groningen to Oradea | 799.05 mi (1,285.95 km) |
| Groningen to Orastie | 899.56 mi (1,447.70 km) |
| Groningen to Oravita | 883.66 mi (1,422.12 km) |
| Groningen to Orsova | 923.65 mi (1,486.46 km) |
| Groningen to Otelu Rosu | 884.14 mi (1,422.89 km) |
| Groningen to Otopeni | 1,064.01 mi (1,712.36 km) |
| Groningen to Ovidiu | 1,170.16 mi (1,883.19 km) |
