Gressholmen Airport Norwegian: Gressholmen sjøflyhavn) was a water aerodrome situated the island of Gressholmen in Oslo, Norway. It served as the main airport serving Oslo from 1927 to 1939, along with Kjeller Airport. The aerodrome consisted of docks, a landing ramp, terminal building and a hangar and used a section of the Oslofjord as its runway. Being located on an island it was necessary to transport passengers by boat to the island.