The Everest Base Camp trek on the south side is one of the most popular trekking routes in the Himalayas and is visited by thousands of trekkers each year. Trekkers usually fly from Kathmandu to Lukla to save time and energy before beginning the morning trek to this base camp. From Lukla, climbers trek upward to the Sherpa capital of Namche Bazaar, 3,440 metres, following the valley of the Dudh Kosi river. Then they trek to Dingboche, 4,260 metres, and then to Everest Base Camp via Gorakshep, the flat field below Kala Patthar, 5,545 metres and Mt. Pumori.