| San Marcos to Orbetello | 6,277.33 mi (10,102.39 km) |
| San Marcos to Oria | 6,590.04 mi (10,605.64 km) |
| San Marcos to Oristano | 6,316.48 mi (10,165.40 km) |
| San Marcos to Orta Nova | 6,483.58 mi (10,434.31 km) |
| San Marcos to Orte | 6,315.20 mi (10,163.32 km) |
| San Marcos to Ortona | 6,386.46 mi (10,278.02 km) |
| San Marcos to Orvieto | 6,292.53 mi (10,126.84 km) |
| San Marcos to Orzinuovi | 6,081.91 mi (9,787.88 km) |
| San Marcos to Osimo | 6,296.45 mi (10,133.16 km) |
| San Marcos to Ospitaletto | 6,078.45 mi (9,782.31 km) |
| San Marcos to Ostuni | 6,575.54 mi (10,582.31 km) |
| San Marcos to Ottaviano | 6,469.72 mi (10,412.00 km) |
| San Marcos to Ovada | 6,078.39 mi (9,782.23 km) |
| San Marcos to Ozieri | 6,296.71 mi (10,133.57 km) |
| San Marcos to Paceco | 6,556.93 mi (10,552.36 km) |
