| Duncan to Orbetello | 5,488.41 mi (8,832.74 km) |
| Duncan to Oria | 5,829.67 mi (9,381.96 km) |
| Duncan to Oristano | 5,485.25 mi (8,827.65 km) |
| Duncan to Orta Nova | 5,716.32 mi (9,199.53 km) |
| Duncan to Orte | 5,534.66 mi (8,907.18 km) |
| Duncan to Ortona | 5,619.34 mi (9,043.46 km) |
| Duncan to Orvieto | 5,512.61 mi (8,871.68 km) |
| Duncan to Orzinuovi | 5,314.38 mi (8,552.67 km) |
| Duncan to Osimo | 5,533.89 mi (8,905.94 km) |
| Duncan to Ospitaletto | 5,313.47 mi (8,551.20 km) |
| Duncan to Ostuni | 5,817.00 mi (9,361.56 km) |
| Duncan to Ottaviano | 5,688.60 mi (9,154.91 km) |
| Duncan to Ovada | 5,294.53 mi (8,520.73 km) |
| Duncan to Ozieri | 5,474.70 mi (8,810.69 km) |
| Duncan to Paceco | 5,734.72 mi (9,229.14 km) |
