Naar was born in The Hague, and was an active climber from the 1970s onwards. He made the first ascents of Peak 6393 in the Karakoram, Djo Drake in Bhutan, Tilleketinda on Greenland and Duivelsei in Surinam. He made the first Dutch ascents of several mountains, including the Eiger (north face) and K2, and was the first Dutch climber to complete the Seven Summits.