Lynam was a civil engineer by profession but devoted most of his life developing the sport of mountaineering in Ireland. He climbed extensively in Ireland, Britain, the Alps and in India. He was leader, or deputy leader, of expeditions to Greenland, the Andes, Kashmir, Tien Shan, Garhwal, Tibet and India, including the 1987 expedition to Changtse, that was the forerunner to the successful first Irish ascent of Everest in 1993.