When most people think about the busiest air routes around the world, New York to Los Angeles or London to Paris spring to mind. It might come as a surprise to some that the world's most crowded flight path is actually between the South Korean island of Jeju and the capital of Seoul. According to UK-based aviation data monitor OAG, there were 64,991 departures between Jeju and Seoul Gimpo in 2017, roughly 178 per day. The route's popularity comes from tourism rather than business travel.
Jeju is the largest island off the Korean peninsula and it is sometimes labeled "the Hawaii of South Korea". It boasts dramatic volcanic landscapes that have been afforded UNESCO World Natural Heritage Site
status as well as impressive hiking trails and stunning beaches. Even though Jeju has lured more international tourists in recent years, particularly from China, the bulk of the visitors are still Korean. In fact, it is so popular among Koreans that a domestic flight from Seoul leaves every 15 minutes on average.
Across the globe, the ten busiest air routes are all domestic and the connection between Melbourne and Sydney is the second busiest. Last year, there were 54,519 departures on the 443 mile route between the two Australian cities. Mumbai to Delhi
comes third with 47,462 departures in 2017. The short hop from Los Angeles to San Francisco is the first American route on the list, coming seventh overall in volume of departures. The busiest international flight path is between Hong Kong and Taipei and it had 29,494 departures in 2017.