| Harlingen to Orbetello | 788.11 mi (1,268.34 km) |
| Harlingen to Oria | 1,045.44 mi (1,682.48 km) |
| Harlingen to Oristano | 928.73 mi (1,494.65 km) |
| Harlingen to Orta Nova | 947.68 mi (1,525.14 km) |
| Harlingen to Orte | 806.65 mi (1,298.17 km) |
| Harlingen to Ortona | 854.60 mi (1,375.35 km) |
| Harlingen to Orvieto | 784.99 mi (1,263.32 km) |
| Harlingen to Orzinuovi | 573.92 mi (923.64 km) |
| Harlingen to Osimo | 763.90 mi (1,229.38 km) |
| Harlingen to Ospitaletto | 566.07 mi (911.00 km) |
| Harlingen to Ostuni | 1,030.09 mi (1,657.78 km) |
| Harlingen to Ottaviano | 950.51 mi (1,529.70 km) |
| Harlingen to Ovada | 607.36 mi (977.45 km) |
| Harlingen to Ozieri | 885.75 mi (1,425.48 km) |
| Harlingen to Paceco | 1,103.29 mi (1,775.57 km) |
