Tasker's first regular climbing partner was Dick Renshaw, whom he had met at university. Together they climbed the North Face of the Eiger in the winter of 1975. This was followed later that year by the first ascent of the South-East ridge of Dunagiri (7066m) in the Gharwal Himalayas. Running out of food and fuel on the descent, they were lucky to survive, although Renshaw suffered frostbite in his fingers.