| Watford to Imola | 751.88 mi (1,210.03 km) |
| Watford to Impruneta | 770.87 mi (1,240.59 km) |
| Watford to Induno Olona | 580.23 mi (933.79 km) |
| Watford to Inverigo | 598.75 mi (963.59 km) |
| Watford to Inveruno | 597.83 mi (962.11 km) |
| Watford to Inzago | 617.64 mi (994.00 km) |
| Watford to Iseo | 630.66 mi (1,014.95 km) |
| Watford to Isernia | 978.68 mi (1,575.03 km) |
| Watford to Isola Capo Rizzuto | 1,215.35 mi (1,955.91 km) |
| Watford to Isola del Liri | 952.74 mi (1,533.28 km) |
| Watford to Isola della Scala | 682.58 mi (1,098.51 km) |
| Watford to Isola Vicentina | 680.92 mi (1,095.84 km) |
| Watford to Ispica | 1,270.99 mi (2,045.46 km) |
| Watford to Istrana | 702.27 mi (1,130.19 km) |
| Watford to Itri | 972.92 mi (1,565.76 km) |
