| Portsmouth to Noventa Vicentina | 695.31 mi (1,118.99 km) |
| Portsmouth to Novi di Modena | 688.45 mi (1,107.95 km) |
| Portsmouth to Novi Ligure | 619.23 mi (996.56 km) |
| Portsmouth to Nuoro | 880.94 mi (1,417.74 km) |
| Portsmouth to Occhiobello | 712.71 mi (1,146.99 km) |
| Portsmouth to Oderzo | 712.76 mi (1,147.08 km) |
| Portsmouth to Oggiono | 591.23 mi (951.49 km) |
| Portsmouth to Olbia | 850.46 mi (1,368.68 km) |
| Portsmouth to Oleggio | 573.43 mi (922.85 km) |
| Portsmouth to Olgiate Comasco | 577.11 mi (928.76 km) |
| Portsmouth to Olgiate Olona | 580.88 mi (934.84 km) |
| Portsmouth to Omegna | 552.47 mi (889.12 km) |
| Portsmouth to Opera | 604.43 mi (972.73 km) |
| Portsmouth to Oppeano | 681.20 mi (1,096.29 km) |
| Portsmouth to Orbassano | 565.03 mi (909.32 km) |
