| Caernarfon to Octeville | 267.82 mi (431.01 km) |
| Caernarfon to Oignies | 360.80 mi (580.65 km) |
| Caernarfon to Oissel | 350.02 mi (563.30 km) |
| Caernarfon to Olivet | 453.99 mi (730.62 km) |
| Caernarfon to Ollioules | 831.92 mi (1,338.85 km) |
| Caernarfon to Olonne-sur-Mer | 469.58 mi (755.72 km) |
| Caernarfon to Oloron-Sainte-Marie | 707.38 mi (1,138.41 km) |
| Caernarfon to Onet Village | 681.39 mi (1,096.60 km) |
| Caernarfon to Onnaing | 386.17 mi (621.48 km) |
| Caernarfon to Orange | 746.16 mi (1,200.83 km) |
| Caernarfon to Orchies | 369.81 mi (595.16 km) |
| Caernarfon to Orleans | 452.01 mi (727.44 km) |
| Caernarfon to Orly | 419.66 mi (675.38 km) |
| Caernarfon to Ormesson-sur-Marne | 421.89 mi (678.96 km) |
| Caernarfon to Orsay | 415.98 mi (669.45 km) |
