Ward, Bourdillon, Riddiford and Murray started a three-week trek by heading west from the Khumbu valley, trying to find the Chola Khola. At the head of this valley they had been told (wrongly) that there was a pass into Tibet, presumably to the West Rongbuk Glacier. However, their map was inaccurate, and they had in fact reached the Ngojumba glacier, the main source of the Dudh Khosi river, at the foot of Cho Oyu. They went north along Cho Oyu's east face but could see no route towards its summit. They then headed for Nup La but progress was slowed by two considerable icefalls so they abandoned the attempt and travelled back to Namche Bazaar improving the mapping of the Chola Khola region as they went.