Halfway through each term, the boys go on a one-week midterm, an expedition through the Siwalik Hills or Himalayas. Senior boys make treks of up to five days, unaccompanied by teachers, camping out in tents and cooking their own food. The trips are planned by students themselves. Alumni have recalled these midterms as formative and character-building experiences. Doon has been credited with pioneering mountaineering in India, due to the accomplishments of masters such as R.L. Holdsworth, Jack Gibson and Gurdial Singh, and alumni like Nandu Jayal, who later became the founder principal of Himalayan Mountaineering Institute. Notable climbs by staff and alumni include Bandarpunch (6,316 m) in 1950, Kala Nag (6,387 m) in 1956, Trisul (7,120 m) in 1951, Kamet (7,756 m) in 1955, Abi Gamin (7,355 m) in 1953 and 1955, Mrigthuni (6,855 m) in 1958 and Jaonli (6,632 metres) in 1964. Some of these expeditions have been noted for their idiosyncrasies. After Gurdial Singh led a successful climb of Trisul, he performed a headstand asana on the summit as a tribute to the Hindu god Shiva, who is said to abide there. Holdsworth smoked a pipe on reaching the summit of Kamet (7,756 m), during its first ascent in 1931. Two Doon pupils climbed the Matterhorn in 1951 wearing cricket boots.