The main international passenger gateway is Helsinki Airport, which handled about 17 million passengers in 2016. Oulu Airport is the second largest, whilst another 25 airports have scheduled passenger services. The Helsinki Airport-based Finnair, Blue1, and Nordic Regional Airlines, Norwegian Air Shuttle sell air services both domestically and internationally. Helsinki has an optimal location for great circle (i.e. the shortest and most efficient) routes between Western Europe and the Far East.