| Helensburgh to Oberkirch | 746.76 mi (1,201.79 km) |
| Helensburgh to Obernburg am Main | 716.25 mi (1,152.70 km) |
| Helensburgh to Obernkirchen | 616.16 mi (991.62 km) |
| Helensburgh to Oberschleissheim | 871.49 mi (1,402.52 km) |
| Helensburgh to Oberstdorf | 872.19 mi (1,403.66 km) |
| Helensburgh to Obertraubling | 858.28 mi (1,381.26 km) |
| Helensburgh to Obertshausen | 695.61 mi (1,119.47 km) |
| Helensburgh to Oberursel | 680.85 mi (1,095.72 km) |
| Helensburgh to Ochsenfurt | 755.89 mi (1,216.48 km) |
| Helensburgh to Ochsenhausen | 827.96 mi (1,332.48 km) |
| Helensburgh to Ochtrup | 549.04 mi (883.59 km) |
| Helensburgh to Odenthal | 594.93 mi (957.45 km) |
| Helensburgh to Oelde | 597.26 mi (961.20 km) |
| Helensburgh to Oelsnitz | 796.13 mi (1,281.25 km) |
| Helensburgh to Oer-Erkenschwick | 573.44 mi (922.86 km) |
