| Castricum to Opwijk | 111.33 mi (179.17 km) |
| Castricum to Ostend | 117.99 mi (189.89 km) |
| Castricum to Oud-Heverlee | 118.61 mi (190.89 km) |
| Castricum to Oud-Turnhout | 86.27 mi (138.84 km) |
| Castricum to Oudenaarde | 126.02 mi (202.82 km) |
| Castricum to Oudenburg | 118.20 mi (190.23 km) |
| Castricum to Oupeye | 133.96 mi (215.59 km) |
| Castricum to Overijse | 122.20 mi (196.66 km) |
| Castricum to Overpelt | 97.52 mi (156.94 km) |
| Castricum to Paal | 106.60 mi (171.56 km) |
| Castricum to Peer | 103.52 mi (166.60 km) |
| Castricum to Pepinster | 145.66 mi (234.42 km) |
| Castricum to Peruwelz | 148.00 mi (238.18 km) |
| Castricum to Perwez | 133.22 mi (214.40 km) |
| Castricum to Philippeville | 162.45 mi (261.43 km) |
