| Belfast to Opole | 1,031.30 mi (1,659.72 km) |
| Belfast to Orzesze | 1,079.06 mi (1,736.59 km) |
| Belfast to Osowa | 973.88 mi (1,567.32 km) |
| Belfast to Ostroda | 1,043.85 mi (1,679.91 km) |
| Belfast to Ostroleka | 1,118.94 mi (1,800.76 km) |
| Belfast to Ostrow Mazowiecka | 1,137.58 mi (1,830.76 km) |
| Belfast to Ostrow Wielkopolski | 1,000.32 mi (1,609.86 km) |
| Belfast to Ostrowiec Swietokrzyski | 1,162.37 mi (1,870.66 km) |
| Belfast to Ostrzeszow | 1,010.88 mi (1,626.86 km) |
| Belfast to Oswiecim | 1,101.23 mi (1,772.25 km) |
| Belfast to Otwock | 1,127.23 mi (1,814.10 km) |
| Belfast to Ozarow Mazowiecki | 1,106.28 mi (1,780.38 km) |
| Belfast to Ozimek | 1,042.27 mi (1,677.37 km) |
| Belfast to Ozorkow | 1,051.36 mi (1,692.00 km) |
| Belfast to Pabianice | 1,063.01 mi (1,710.75 km) |
