| Opmeer to Montemor-o-Novo | 1,156.33 mi (1,860.93 km) |
| Opmeer to Montemor-o-Velho | 1,078.45 mi (1,735.59 km) |
| Opmeer to Montijo | 1,172.32 mi (1,886.67 km) |
| Opmeer to Mortagua | 1,050.27 mi (1,690.25 km) |
| Opmeer to Moura | 1,168.73 mi (1,880.89 km) |
| Opmeer to Murtosa | 1,044.04 mi (1,680.22 km) |
| Opmeer to Nazare | 1,122.43 mi (1,806.38 km) |
| Opmeer to Nelas | 1,034.82 mi (1,665.38 km) |
| Opmeer to Obidos | 1,139.22 mi (1,833.40 km) |
| Opmeer to Odemira | 1,231.99 mi (1,982.70 km) |
| Opmeer to Odivelas | 1,173.49 mi (1,888.55 km) |
| Opmeer to Oeiras | 1,183.61 mi (1,904.83 km) |
| Opmeer to Olhao | 1,246.85 mi (2,006.61 km) |
| Opmeer to Oliveira de Azemeis | 1,033.34 mi (1,663.01 km) |
| Opmeer to Oliveira de Frades | 1,032.28 mi (1,661.29 km) |
