The city whose nearest neighbour is 3,854km away
For any city you can work out the distance to its nearest other city. For Seoul that is Incheon, 27km. Sort all 524 cities in the dictionary by that value and you get a ranking that does not show up on a map.
| City | Nearest city | Distance |
|---|---|---|
| Honolulu (USA) | San Francisco | 3,854km |
| Hanga Roa (Chile) | Puerto Ayora | 3,576km |
| Tarawa (Kiribati) | Honiara | 1,874km |
| Dakar (Senegal) | Abidjan | 1,803km |
| Victoria (Seychelles) | Port Louis | 1,742km |
First and second are in the 3,000s, then third drops straight to the 1,800s. That is the size of the break between the middle of the Pacific and everywhere else. Hanga Roa is Easter Island; Puerto Ayora is the Galápagos. The neighbour of a remote place is another remote place.
It is the same whichever way you leave
What makes Honolulu unusual is not its rank but its symmetry.
- Northeast, 3,854km — San Francisco
- West-southwest, 3,863km — Tarawa
Nine kilometres apart. Two neighbours in opposite directions at almost exactly the same distance. After those: Los Angeles east-northeast at 4,120km, Portland northeast at 4,175km, Apia south-southwest at 4,193km. Whichever way you set out, there is nothing inside 4,000km.
Seoul to Honolulu is 7,312km, due east. The time difference is 19 hours behind, though it is easier to think of it as being a day back.
This is a story about our dictionary, not about the Earth
Worth stating clearly: this ranking is based on our 524 cities. The Hawaiian islands have plenty of inhabited islands and towns besides Honolulu, and the Pacific holds far more islands than we included. A city that is not in the dictionary does not enter the calculation.
So the heading on this table is not "the most remote city on Earth" but "the city with the most distant neighbour when this service builds an itinerary." Those are different questions, and the second is the one we can answer.
A remote city cannot be used as a stopover
This value does real work. It shows up directly in the detour ratio used to pick waypoints.
The direct distance from Seoul to Paris is 8,966km. Slot in Dalian and it becomes 9,068km, a ratio of 1.01. Slot in Honolulu and it becomes 19,281km, a ratio of 2.15. You would be heading out to the far side of the Pacific and back in order to reach Paris. This service cuts candidates off at 1.4, so Honolulu never lands on a route to Europe.
A city with distant neighbours makes a fine destination and a useless stopover, for the simple reason that it is not on the way to anywhere. Places like that only appear on screen when you decide to go.