In Istanbul the ferry changes your continent
"Two continents, one ferry ride." That is the line CouchColumbus attaches to Istanbul, and it is less a metaphor than a description of the geography. The Bosphorus runs through the middle of the city; the western bank is Europe and the eastern bank is Asia. Board a ferry at Üsküdar or Kadıköy, get off on the other side, and you have crossed a continent on the way. At its narrowest the strait is under a kilometre across.
In our city dictionary Istanbul is stored as 41.0082, 28.9784. It is one point, but the city it stands for is split either side of that point, and what splits it is not a river but a sea.
All four places we pinned are on the European side
The spots the service attaches to Istanbul are Hagia Sophia, the Sultan Ahmed Mosque, Topkapı Palace and the Grand Bazaar. Count them and all four sit west of the strait, on the European side. A city with two continents, and our picks are bunched on one of them.
That says more about lists than about the city. UNESCO's world heritage listing from 1985 is called the Historic Areas of Istanbul, and its bounds gather around the old walled city. UNESCO on the Historic Areas of Istanbul Markers collect where names have been attached the longest, and that happens in every city. The side of the map that looks empty is not the side with nothing on it; it is the side we have not pinned yet.
7,954km from Seoul, and the line leaves to the northwest
From Seoul's reference coordinates, measured along the great circle — the shortest path on a sphere — Istanbul is 7,954km away on a departure bearing of northwest. On the map that line is drawn as a curve bulging upward, because a flat map is a curved surface unfolded. We wrote that part up in the line to Paris.
Summarise the land under the route by country and it starts in South Korea and runs through North Korea, China, Mongolia, Russia and Kazakhstan before entering Türkiye. Through Central Asia it crosses back and forth over the Russia–Kazakhstan border several times. Almost none of it is over water; it is a route that stays over land.
9.9 hours and six hours
The service's simple conversion — 850km/h plus half an hour of ground travel — gives about 9.9 hours. It is the distance between two coordinates expressed as time, not a real flight.
The time difference is six hours, with Istanbul behind Seoul. Leave Seoul at noon, fly for 9.9 hours, and you arrive at what is 10pm in Seoul while the local clocks still read 4pm. The journey runs in the direction that makes the day longer. For the record, the point on the far side of the Earth from Istanbul is 41°S, 151°W — open water in the South Pacific, no land at all.
The population is roughly 15.7 million according to GeoNames. That puts it among the largest in our 524 cities, and those people live divided across the two banks of a strait.
The cities that lie on the way
Draw the line from Seoul to Istanbul and 243 cities fall inside the 1.4 detour ratio we use for waypoints. Sorted by distance from the origin, the first few look like this.
| City | From Seoul | Detour ratio |
|---|---|---|
| Dalian | 493km | 1.00 |
| Fukuoka | 540km | 1.13 |
| Qingdao | 610km | 1.03 |
| Vladivostok | 747km | 1.09 |
Dalian scores 1.00, meaning the great circle from Seoul to Istanbul passes directly over it. Fukuoka is at 1.13: much the same distance from Seoul, but on the wrong side, so you double back by that much. Being on the way is a question of direction, not of distance.
Build the journey and play it, and the line climbs to 51°N, brushes past the north of the Caspian and crosses the Black Sea on the way down. Istanbul sits at 41°N, so the route detours ten degrees further north than its destination. Then it stops on a point with a strait running through it. The ferry part does not appear on screen.