| Mason City to Orbetello | 4,897.59 mi (7,881.91 km) |
| Mason City to Oria | 5,230.97 mi (8,418.44 km) |
| Mason City to Oristano | 4,910.63 mi (7,902.90 km) |
| Mason City to Orta Nova | 5,119.28 mi (8,238.68 km) |
| Mason City to Orte | 4,941.17 mi (7,952.04 km) |
| Mason City to Ortona | 5,021.83 mi (8,081.85 km) |
| Mason City to Orvieto | 4,918.81 mi (7,916.05 km) |
| Mason City to Orzinuovi | 4,715.63 mi (7,589.07 km) |
| Mason City to Osimo | 4,934.56 mi (7,941.41 km) |
| Mason City to Ospitaletto | 4,713.90 mi (7,586.30 km) |
| Mason City to Ostuni | 5,217.68 mi (8,397.05 km) |
| Mason City to Ottaviano | 5,095.98 mi (8,201.19 km) |
| Mason City to Ovada | 4,701.09 mi (7,565.68 km) |
| Mason City to Ozieri | 4,896.25 mi (7,879.76 km) |
| Mason City to Paceco | 5,157.46 mi (8,300.13 km) |
