| Halden to Orbetello | 1,153.02 mi (1,855.60 km) |
| Halden to Oria | 1,314.51 mi (2,115.51 km) |
| Halden to Oristano | 1,334.03 mi (2,146.91 km) |
| Halden to Orta Nova | 1,243.07 mi (2,000.53 km) |
| Halden to Orte | 1,152.17 mi (1,854.23 km) |
| Halden to Ortona | 1,165.86 mi (1,876.27 km) |
| Halden to Orvieto | 1,134.01 mi (1,825.01 km) |
| Halden to Orzinuovi | 950.60 mi (1,529.84 km) |
| Halden to Osimo | 1,084.16 mi (1,744.79 km) |
| Halden to Ospitaletto | 939.50 mi (1,511.99 km) |
| Halden to Ostuni | 1,298.18 mi (2,089.22 km) |
| Halden to Ottaviano | 1,269.45 mi (2,042.98 km) |
| Halden to Ovada | 1,008.02 mi (1,622.26 km) |
| Halden to Ozieri | 1,285.63 mi (2,069.02 km) |
| Halden to Paceco | 1,461.62 mi (2,352.24 km) |
