| Watford to Mangualde | 840.03 mi (1,351.89 km) |
| Watford to Marco de Canavezes | 811.27 mi (1,305.61 km) |
| Watford to Marinha Grande | 918.49 mi (1,478.16 km) |
| Watford to Massama | 988.76 mi (1,591.25 km) |
| Watford to Matosinhos | 823.36 mi (1,325.07 km) |
| Watford to Mealhada | 868.16 mi (1,397.17 km) |
| Watford to Melgaco | 755.61 mi (1,216.03 km) |
| Watford to Melres | 823.99 mi (1,326.09 km) |
| Watford to Mira | 871.05 mi (1,401.82 km) |
| Watford to Miranda do Corvo | 883.74 mi (1,422.24 km) |
| Watford to Mirandela | 772.25 mi (1,242.82 km) |
| Watford to Mogadouro | 773.23 mi (1,244.40 km) |
| Watford to Moimenta da Beira | 813.09 mi (1,308.55 km) |
| Watford to Moita | 989.59 mi (1,592.60 km) |
| Watford to Moncao | 763.22 mi (1,228.29 km) |
