Steiner started mountain-climbing at the age of 17 and went on to climb the Eiger, Matterhorn and Grandes Jorasses. He then climbed Bigwall in British Columbia and took part in expeditions to Mount Everest, Langtang in Tibet, Rolwaling and Tien Shan. In 1997 he had a serious accident at Grandes Jorasses which made him review his attitude to climbing, after which he wrote his first book.