| Gourock to Orbetello | 1,175.38 mi (1,891.59 km) |
| Gourock to Oria | 1,472.90 mi (2,370.41 km) |
| Gourock to Oristano | 1,265.70 mi (2,036.94 km) |
| Gourock to Orta Nova | 1,367.70 mi (2,201.09 km) |
| Gourock to Orte | 1,206.49 mi (1,941.66 km) |
| Gourock to Ortona | 1,271.15 mi (2,045.72 km) |
| Gourock to Orvieto | 1,183.88 mi (1,905.27 km) |
| Gourock to Orzinuovi | 970.05 mi (1,561.15 km) |
| Gourock to Osimo | 1,180.57 mi (1,899.95 km) |
| Gourock to Ospitaletto | 965.41 mi (1,553.68 km) |
| Gourock to Ostuni | 1,458.34 mi (2,346.97 km) |
| Gourock to Ottaviano | 1,358.82 mi (2,186.80 km) |
| Gourock to Ovada | 978.36 mi (1,574.51 km) |
| Gourock to Ozieri | 1,232.44 mi (1,983.43 km) |
| Gourock to Paceco | 1,478.14 mi (2,378.83 km) |
