The Dublin-London air route is the second busiest international corridor in the world as 3.6 million passengers jetted between the capital cities last year. That's up almost 7% on 2012, according to the latest figures from the International Air Transport Association (IATA).
Aer Lingus, Ryanair, CityJet, Flybe and British Airways all compete on routes between Dublin and the four main London airports.
The busiest international route is between Hong Kong and Chinese Taipei, with 4.9 million people using the route last year, although that is down 11.5%.
In third place is Jakarta to Singapore, which carried 3.4 million passengers.
The United States remains the largest single air market in the world in terms of both domestic and international travel.
Overall, the world's airlines carried 3.13 billion passengers across the globe in 2013 – an increase of 5.1% on the previous year. Airlines in the Asia-Pacific region carried the largest number of passengers, at one billion, followed by Europe at 826 million passengers.