| Watford to Oerlinghausen | 387.47 mi (623.57 km) |
| Watford to Oestrich-Winkel | 383.59 mi (617.33 km) |
| Watford to Offenburg | 429.75 mi (691.62 km) |
| Watford to Oftersheim | 424.61 mi (683.35 km) |
| Watford to Ohrdruf | 484.26 mi (779.34 km) |
| Watford to Ohringen | 466.97 mi (751.51 km) |
| Watford to Olbernhau | 597.90 mi (962.22 km) |
| Watford to Olching | 572.19 mi (920.85 km) |
| Watford to Oldenburg | 376.99 mi (606.71 km) |
| Watford to Oldenburg in Holstein | 502.88 mi (809.30 km) |
| Watford to Olfen | 333.09 mi (536.06 km) |
| Watford to Olpe | 357.75 mi (575.74 km) |
| Watford to Olsberg | 382.22 mi (615.13 km) |
| Watford to Oranienburg | 581.33 mi (935.56 km) |
| Watford to Ortenberg | 420.27 mi (676.35 km) |
