| Harwich to Olivares | 1,065.82 mi (1,715.27 km) |
| Harwich to Olivenza | 1,000.01 mi (1,609.36 km) |
| Harwich to Olot | 676.21 mi (1,088.26 km) |
| Harwich to Onate | 638.35 mi (1,027.32 km) |
| Harwich to Onda | 830.36 mi (1,336.33 km) |
| Harwich to Onteniente | 910.41 mi (1,465.16 km) |
| Harwich to Orihuela | 962.80 mi (1,549.48 km) |
| Harwich to Osuna | 1,061.91 mi (1,708.98 km) |
| Harwich to Ourense | 788.49 mi (1,268.96 km) |
| Harwich to Oviedo | 677.85 mi (1,090.90 km) |
| Harwich to Paiporta | 867.85 mi (1,396.67 km) |
| Harwich to Pajara | 1,811.87 mi (2,915.92 km) |
| Harwich to Palafolls | 712.66 mi (1,146.91 km) |
| Harwich to Palafrugell | 697.78 mi (1,122.97 km) |
| Harwich to Palamos | 702.49 mi (1,130.55 km) |
