Keflavik International Airport — Reykjavík, Iceland

Keflavík International Airport, coded KEF, occupies the Reykjanes Peninsula roughly 30 miles from Reykjavík, serving as Iceland's overwhelming gateway for international air travel. The site began as a military airfield built during the Second World War and later operated for decades as a NATO installation, Naval Air Station Keflavik, before transitioning fully to civilian control. Icelandair built its business model around KEF's geographic position between North America and Europe, offering stopover itineraries that let travelers break up transatlantic journeys with a few days in Iceland at little extra cost, a strategy that turned the airport into a genuine hub rather than a simple endpoint. The nearby Blue Lagoon geothermal spa, formed from runoff of an adjacent power plant, has become a near-mandatory stop for arriving and departing passengers.