On a top 10 list packed with surprises, in first place is the route between Seoul's Gimpo Airport and the South Korean resort island of Jeju, according to travel technology group Amadeus.
More than 10 million air passenger movements were recorded on this route in 2015.
What is even more surprising, is that Gimpo is not even the capital's main airport, which is Incheon.
In second place is Tokyo to Sapporo, followed by another Japanese domestic route, Tokyo to Fukuoka.
In fourth place is the Melbourne-Sydney, route with close to 8 million passenger movements in 2015, followed by Beijing to Shanghai.
No European or North American airports appear on the list of the 10 busiest air routes, and apart from Sao Paolo to Rio de Janeiro, all lie within the Asia-Pacific region.
The only non-domestic flight on the top 10 list is Taipei to Hong Kong.
Only the Shanghai-Beijing and Tokyo-Okinawa flights are longer than 1000 kilometres.
Another big surprise is the appearance of Tokyo-Osaka on the list, since the fastest Shinkansen trains make the journey in just over 2½ hours.
Finally, most of these routes are dominated by leisure travellers, rather than those on business.
Busy air routes are good news for travellers since they attract several different carriers, which usually guarantees competitive pricing among full-service carriers as well as budget airlines, and a wide choice of flight times.
