The river drains the Mount Everest massif, the highest peak in the world. It begins just east of Gokyo Lakes and flows south to Namche Bazaar. Continuing south, the Dudh Koshi exits Sagarmatha National Park and passes to the west of Lukla. The Lamding Khola joins the Dudh Koshi to the southwest of Surkya and continues its southerly course to Harkapur, where it joins the Sun Kosi.