| Helensburgh to Orbetello | 1,176.24 mi (1,892.98 km) |
| Helensburgh to Oria | 1,472.93 mi (2,370.45 km) |
| Helensburgh to Oristano | 1,267.45 mi (2,039.77 km) |
| Helensburgh to Orta Nova | 1,367.91 mi (2,201.44 km) |
| Helensburgh to Orte | 1,207.12 mi (1,942.67 km) |
| Helensburgh to Ortona | 1,271.43 mi (2,046.16 km) |
| Helensburgh to Orvieto | 1,184.52 mi (1,906.30 km) |
| Helensburgh to Orzinuovi | 970.61 mi (1,562.04 km) |
| Helensburgh to Osimo | 1,180.81 mi (1,900.33 km) |
| Helensburgh to Ospitaletto | 965.91 mi (1,554.47 km) |
| Helensburgh to Ostuni | 1,458.34 mi (2,346.98 km) |
| Helensburgh to Ottaviano | 1,359.32 mi (2,187.62 km) |
| Helensburgh to Ovada | 979.37 mi (1,576.14 km) |
| Helensburgh to Ozieri | 1,234.03 mi (1,985.98 km) |
| Helensburgh to Paceco | 1,479.37 mi (2,380.82 km) |
