Have anyone else climbed the Mountain *twice* to get that Question Mark, near to Skellige stronghold (Kaer Trolde citadel ) just to realize ,it will be unlocked later in the main story? :( :
The Witcher 3 Wild Hunt: Witcher contracts in Kaer Trolde - list, walkthrough | gamepressure.com
Steam Community :: Guide :: Wiedźmin 3 Dziki Gon Poradnik Osiągnięcia (Achievement Guide)