In late July 2009, two female king eiders were caught on the breeding grounds in Myggbukta, Northeast Greenland and equipped with satellite transmitters. Both individuals were tracked for approximately two years. The birds remained in the Myggbukta area until the onset of the autumn migration in the beginning of August (median day of departure 9 August, range 2 August – 15 August). Both individuals moved directly to the southwest coast of Spitsbergen where they apparently moulted within known moulting areas of the Svalbard breeding population. They spent the autumn from approximately 12 August – 13 November along the southwest coast of Spitsbergen, before moving to the shallow offshore Spitsbergenbanken in the Barents Sea and the coast of Bjørnøya (Bear Island) for the winter (median dates 13 November - 6 April). In spring, the king eiders returned to the southwest coast of Spitsbergen (median arrival 6 April) where they stayed for some time before returning on the spring migration to Greenland. During a ship-based survey in the offshore winter location at Spitsbergenbanken in April 2013, a previously unknown wintering ground with approximately 10.000 king eiders was discovered. The birds were concentrated in a partly ice-covered area 79 km from shore and of about 20 m depth. The number of king eiders indicated that Spitsbergenbanken is a wintering area for both the East Greenland and the Svalbard breeding populations. The discovery has important conservation implications due to the expanding petroleum and shipping activity in the Barents Sea.