| Mount Washington to Orbetello | 4,814.00 mi (7,747.38 km) |
| Mount Washington to Oria | 5,162.42 mi (8,308.11 km) |
| Mount Washington to Oristano | 4,795.85 mi (7,718.18 km) |
| Mount Washington to Orta Nova | 5,047.68 mi (8,123.45 km) |
| Mount Washington to Orte | 4,862.92 mi (7,826.11 km) |
| Mount Washington to Ortona | 4,951.77 mi (7,969.11 km) |
| Mount Washington to Orvieto | 4,841.32 mi (7,791.35 km) |
| Mount Washington to Orzinuovi | 4,650.01 mi (7,483.47 km) |
| Mount Washington to Osimo | 4,869.00 mi (7,835.90 km) |
| Mount Washington to Ospitaletto | 4,650.12 mi (7,483.64 km) |
| Mount Washington to Ostuni | 5,150.56 mi (8,289.03 km) |
| Mount Washington to Ottaviano | 5,015.10 mi (8,071.02 km) |
| Mount Washington to Ovada | 4,624.02 mi (7,441.63 km) |
| Mount Washington to Ozieri | 4,788.55 mi (7,706.43 km) |
| Mount Washington to Paceco | 5,046.41 mi (8,121.41 km) |
