| Shannon to Marco de Canavezes | 797.38 mi (1,283.26 km) |
| Shannon to Marinha Grande | 895.71 mi (1,441.51 km) |
| Shannon to Massama | 964.52 mi (1,552.25 km) |
| Shannon to Matosinhos | 796.71 mi (1,282.18 km) |
| Shannon to Mealhada | 852.18 mi (1,371.45 km) |
| Shannon to Melgaco | 732.72 mi (1,179.19 km) |
| Shannon to Melres | 805.03 mi (1,295.57 km) |
| Shannon to Mira | 848.52 mi (1,365.56 km) |
| Shannon to Miranda do Corvo | 871.89 mi (1,403.17 km) |
| Shannon to Mirandela | 779.80 mi (1,254.96 km) |
| Shannon to Mogadouro | 792.72 mi (1,275.76 km) |
| Shannon to Moimenta da Beira | 812.87 mi (1,308.19 km) |
| Shannon to Moita | 971.72 mi (1,563.84 km) |
| Shannon to Moncao | 735.40 mi (1,183.52 km) |
| Shannon to Montalegre | 754.14 mi (1,213.67 km) |
