| Mercer Island to Olivares | 5,369.34 mi (8,641.12 km) |
| Mercer Island to Olivenza | 5,268.55 mi (8,478.92 km) |
| Mercer Island to Olot | 5,377.53 mi (8,654.30 km) |
| Mercer Island to Onate | 5,183.54 mi (8,342.10 km) |
| Mercer Island to Onda | 5,420.33 mi (8,723.18 km) |
| Mercer Island to Onteniente | 5,473.54 mi (8,808.81 km) |
| Mercer Island to Orihuela | 5,504.04 mi (8,857.89 km) |
| Mercer Island to Osuna | 5,414.89 mi (8,714.43 km) |
| Mercer Island to Ourense | 5,048.36 mi (8,124.55 km) |
| Mercer Island to Oviedo | 5,058.96 mi (8,141.62 km) |
| Mercer Island to Paiporta | 5,445.52 mi (8,763.71 km) |
| Mercer Island to Pajara | 5,559.51 mi (8,947.16 km) |
| Mercer Island to Palafolls | 5,414.37 mi (8,713.58 km) |
| Mercer Island to Palafrugell | 5,412.16 mi (8,710.03 km) |
| Mercer Island to Palamos | 5,415.26 mi (8,715.02 km) |
