Aavatsmarkbreen is a glacier in Oscar II Land at Spitsbergen, Svalbard. It is named after politician and military officer Ivar Aavatsmark. The glacier debouches into Forlandsundet, in the bay of Hornbækbukta.[1][2][3] At the southern side of the glacier, between Aavatsmarkbreen and Kaffiøyra, is the mountain range of Prins Heinrichfjella.[4][5]