Dujmovits' mountaineering career began with the German Alpine Club, where he worked as a guide and led clients on international expeditions including highest mountains on six of the seven continents. He also climbed extensively in the Alps, with and without clients, making successful ascents of the Matterhorn, the Eiger, Mont Blanc, the Grosshorn, Les Courtes, Laliderer, the Reissend Nollen, and peaks in the Engelhorn Range. In 1989, he left the German Alpine Club to start up his own trekking outfitter, Amical Alpin.