| Enfield Lock to Orbetello | 826.64 mi (1,330.34 km) |
| Enfield Lock to Oria | 1,139.79 mi (1,834.31 km) |
| Enfield Lock to Oristano | 911.17 mi (1,466.38 km) |
| Enfield Lock to Orta Nova | 1,030.52 mi (1,658.46 km) |
| Enfield Lock to Orte | 861.42 mi (1,386.32 km) |
| Enfield Lock to Ortona | 933.08 mi (1,501.64 km) |
| Enfield Lock to Orvieto | 838.74 mi (1,349.82 km) |
| Enfield Lock to Orzinuovi | 627.63 mi (1,010.07 km) |
| Enfield Lock to Osimo | 843.95 mi (1,358.20 km) |
| Enfield Lock to Ospitaletto | 624.47 mi (1,004.99 km) |
| Enfield Lock to Ostuni | 1,126.01 mi (1,812.14 km) |
| Enfield Lock to Ottaviano | 1,015.54 mi (1,634.36 km) |
| Enfield Lock to Ovada | 628.15 mi (1,010.90 km) |
| Enfield Lock to Ozieri | 877.91 mi (1,412.87 km) |
| Enfield Lock to Paceco | 1,125.14 mi (1,810.75 km) |
