| Greenock to Oberkirch | 744.87 mi (1,198.76 km) |
| Greenock to Obernburg am Main | 714.97 mi (1,150.63 km) |
| Greenock to Obernkirchen | 615.84 mi (991.10 km) |
| Greenock to Oberschleissheim | 870.17 mi (1,400.40 km) |
| Greenock to Oberstdorf | 870.44 mi (1,400.83 km) |
| Greenock to Obertraubling | 857.25 mi (1,379.62 km) |
| Greenock to Obertshausen | 694.34 mi (1,117.44 km) |
| Greenock to Oberursel | 679.58 mi (1,093.68 km) |
| Greenock to Ochsenfurt | 754.71 mi (1,214.59 km) |
| Greenock to Ochsenhausen | 826.31 mi (1,329.82 km) |
| Greenock to Ochtrup | 548.33 mi (882.46 km) |
| Greenock to Odenthal | 593.68 mi (955.43 km) |
| Greenock to Oelde | 596.56 mi (960.08 km) |
| Greenock to Oelsnitz | 795.56 mi (1,280.33 km) |
| Greenock to Oer-Erkenschwick | 572.48 mi (921.32 km) |
