| Delaware to Orbetello | 4,614.12 mi (7,425.71 km) |
| Delaware to Oria | 4,961.65 mi (7,985.00 km) |
| Delaware to Oristano | 4,598.82 mi (7,401.08 km) |
| Delaware to Orta Nova | 4,847.05 mi (7,800.57 km) |
| Delaware to Orte | 4,662.66 mi (7,503.82 km) |
| Delaware to Ortona | 4,750.97 mi (7,645.95 km) |
| Delaware to Orvieto | 4,640.99 mi (7,468.95 km) |
| Delaware to Orzinuovi | 4,448.72 mi (7,159.52 km) |
| Delaware to Osimo | 4,667.84 mi (7,512.17 km) |
| Delaware to Ospitaletto | 4,448.71 mi (7,159.50 km) |
| Delaware to Ostuni | 4,949.68 mi (7,965.75 km) |
| Delaware to Ottaviano | 4,815.15 mi (7,749.23 km) |
| Delaware to Ovada | 4,423.50 mi (7,118.93 km) |
| Delaware to Ozieri | 4,590.79 mi (7,388.17 km) |
| Delaware to Paceco | 4,849.21 mi (7,804.05 km) |
