| Harwich to Orbetello | 803.71 mi (1,293.45 km) |
| Harwich to Oria | 1,107.04 mi (1,781.61 km) |
| Harwich to Oristano | 901.47 mi (1,450.78 km) |
| Harwich to Orta Nova | 999.63 mi (1,608.75 km) |
| Harwich to Orte | 835.31 mi (1,344.31 km) |
| Harwich to Ortona | 902.55 mi (1,452.52 km) |
| Harwich to Orvieto | 812.67 mi (1,307.87 km) |
| Harwich to Orzinuovi | 599.37 mi (964.59 km) |
| Harwich to Osimo | 812.52 mi (1,307.63 km) |
| Harwich to Ospitaletto | 595.20 mi (957.88 km) |
| Harwich to Ostuni | 1,092.90 mi (1,758.85 km) |
| Harwich to Ottaviano | 988.25 mi (1,590.43 km) |
| Harwich to Ovada | 606.91 mi (976.73 km) |
| Harwich to Ozieri | 865.72 mi (1,393.25 km) |
| Harwich to Paceco | 1,107.68 mi (1,782.64 km) |
