| San Diego to Orbetello | 6,292.70 mi (10,127.12 km) |
| San Diego to Oria | 6,606.03 mi (10,631.38 km) |
| San Diego to Oristano | 6,331.02 mi (10,188.79 km) |
| San Diego to Orta Nova | 6,499.41 mi (10,459.79 km) |
| San Diego to Orte | 6,330.73 mi (10,188.32 km) |
| San Diego to Ortona | 6,402.27 mi (10,303.45 km) |
| San Diego to Orvieto | 6,308.06 mi (10,151.85 km) |
| San Diego to Orzinuovi | 6,097.59 mi (9,813.13 km) |
| San Diego to Osimo | 6,312.30 mi (10,158.67 km) |
| San Diego to Ospitaletto | 6,094.18 mi (9,807.63 km) |
| San Diego to Ostuni | 6,591.56 mi (10,608.09 km) |
| San Diego to Ottaviano | 6,485.29 mi (10,437.07 km) |
| San Diego to Ovada | 6,093.78 mi (9,806.99 km) |
| San Diego to Ozieri | 6,311.43 mi (10,157.26 km) |
| San Diego to Paceco | 6,571.74 mi (10,576.19 km) |
