
Korea’s Jeju Island is a tourist hot spot. (Image: Visit Korea)
Have you ever been to Jeju Island? Probably not, unless you’re Korean. But travelers who go there are flying the world’s busiest air route.
Jeju is off the southern tip of the Korean peninsula; it’s got lots of beach resorts, a dormant volcano and a miles-long natural cave. It’s a favorite vacation spot for Koreans who want to get away from the hustle and bustle of the capital city, and in July 2017, almost 1.3 million persons flew between Jeju and Seoul (not Seoul Incheon, but Seoul Gimpo, nine miles west of the city).
A new study by Routesonline.com found that those passengers were accommodated on more than 5,800 flights between the two airports during July, or an average of 189 flights a day.
The study determined the world’s busiest air routes in terms of passenger numbers, and of the top 20, exactly none were in North America, Europe or South America. Almost all of them were in the Asia-Pacific region, mostly on domestic routes.

Chart: Routesonline.com
Ranking a distant second behind Seoul-Jeju was a domestic Japanese route, Tokyo Haneda to Sapporo New Chitose. (You might remember Sapporo, on Japan’s northern island of Hokkaido, as the site of the 1972 Winter Olympics – or as the name of a popular Japanese beer.)
The third-busiest route worldwide during July was one more likely to see Western travelers: Melbourne to Sydney’s Kingsford Smith Airport.
Rounding out the top 10 routes in passenger numbers were Tokyo Haneda-Fukuoka in Japan; Delhi-Mumbai in India; Ho Chi Minh City (Saigon)-Hanoi in Vietnam; Shanghai Hongqiao-Beijing in China; Hong Kong-Taipei; Okinawa-Tokyo Haneda; and an Indonesian route, Jakarta-Surabaya.
What are the busiest routes in the US? We could not find a study that showed just July numbers like the one above, but World Atlas provides this list of the USA’s busiest over the full year from Aug 2014-Aug 2015– in millions of passengers. It’s probably not changed much since then.

Top 10 busiest air routes (in millions of passengers) in the US Aug 2014-Aug 2015 (Source: World Atlas)
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I just went to Jeju a week and a half ago. I loved it. There is no surprise it’s a really busy airway. The flight is only 1 hour from Gimpo and really cheap! Especially if you buy months in advance.
Jeju Island is absolutely lovely — its Nutmeg Forest (the largest free-standing grove of nutmeg trees on the planet) is nothing short of enchanting. I’ve been four times (to date); Korean tech companies love holding conferences there as an excuse to get out of Seoul themselves! The airport and Jeju City proper are pretty hectic, but once you get beyond that it’s rather bucolic. I highly recommend renting a car — I’ve done it every time after my first trip (when I wound up relying on a colleague who had rented a car because it’s impossible to get around and away from the expensive resort areas without one). All it takes is an international driver’s license, which is available to any licensed US driver for around $10 (and can be procured at a AAA office).
I’m wondering whether the US numbers include trips originating and terminating at all airports when cities have multiple airports. Do the New York trips include flights to and from LaGuardia, JFK and Newark? What about Chicago which has O’Hare and Midway, or Los Angeles with LAX, Burbank, Long Beach, Orange County and Ontario?
Will be going to Jeju (CJU) next week. Have been there 12-15 times. It is crazy! We’re not talking about MD-88 or 737. I will be on a 787 next week. These planes are packed too. 777, 747, 330. Packed deep and cheap. Median age is probably 16 years old. Kids everywhere. You can walk up to the ticket counter 10 minutes before boarding, through security and on your flight with time to spare. If you go to Jeju island at the right time get the tangerines. They are my favorite. It is the Puerto Rico of Korea. Chinese people pack the place as visitors but have been banned this year for political reasons. I think it still is in place.
Interesting! Thanks for the first hand report. Sounds crazy.
I’ve flown Jeju -> Seoul. The airport in Jeju is absolutely nuts. They are literally turning around flights at a single gate every 20 minutes. They’d often be queing up 2 flights at once at the same gate.
While waiting for my flight, I just watched people almost running off their flight, and then people being herded onto the plane immediately afterwards. I can’t imagine that anyone was cleaning up the planes in between, as there was literally no time gap between off boarding & on boarding.