| Caister-on-Sea to Mangualde | 944.58 mi (1,520.16 km) |
| Caister-on-Sea to Marco de Canavezes | 917.52 mi (1,476.61 km) |
| Caister-on-Sea to Marinha Grande | 1,024.52 mi (1,648.80 km) |
| Caister-on-Sea to Massama | 1,094.31 mi (1,761.12 km) |
| Caister-on-Sea to Matosinhos | 930.75 mi (1,497.89 km) |
| Caister-on-Sea to Mealhada | 973.98 mi (1,567.47 km) |
| Caister-on-Sea to Melgaco | 863.42 mi (1,389.54 km) |
| Caister-on-Sea to Melres | 930.62 mi (1,497.69 km) |
| Caister-on-Sea to Mira | 977.53 mi (1,573.19 km) |
| Caister-on-Sea to Miranda do Corvo | 988.94 mi (1,591.54 km) |
| Caister-on-Sea to Mirandela | 876.64 mi (1,410.82 km) |
| Caister-on-Sea to Mogadouro | 876.14 mi (1,410.01 km) |
| Caister-on-Sea to Moimenta da Beira | 917.82 mi (1,477.09 km) |
| Caister-on-Sea to Moita | 1,094.43 mi (1,761.31 km) |
| Caister-on-Sea to Moncao | 871.39 mi (1,402.37 km) |
